document.write( "Question 1210613: Marek and Zaven had 900 coins altogether. Marek spent 25% fewer coins than Zaven. Zaven was left with 50% as many coins as the number he spent. Marek had 75% of the total number of coins the two friends had left in the end. How many coins did Marek have in the end?
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #854416 by KMST(5362)\"\" \"About 
You can put this solution on YOUR website!
DATA WE HAVE:
\n" ); document.write( "Marek and Zaven had 900 coins altogether.
\n" ); document.write( "That is what they had initially.
\n" ); document.write( "
\n" ); document.write( "Zaven was left with 50% (half) as many coins as the number he spent.
\n" ); document.write( "He spent twice as many coins as he was left with.
\n" ); document.write( "For every 1 coin he had left, there were 2 he had spent, and 3 that he originally had.
\n" ); document.write( "That tells me that the number of coins Zaven initially had was a multiple of 3.
\n" ); document.write( "
\n" ); document.write( "Marek spent 25% fewer coins than Zaven.
\n" ); document.write( "Marek spent 100%-25%=75% of what Zaven spent.
\n" ); document.write( "If I knew how much Zaven spent I can multiply times 0.75 to find what Marek spent.
\n" ); document.write( "For every 4 coins Zaven spent Marek spent 3. So I could instead divide by 4 and multiply times 3.
\n" ); document.write( "
\n" ); document.write( "Marek had 75% of the total number of coins the two friends had left in the end.
\n" ); document.write( "
\n" ); document.write( "Could Marek have initially had 75% of the total number of coins the two friends had left in the end? It does not seem possible.
\n" ); document.write( "I think what the \"in the end\" part applies to the whole sentence, and what was meant is:
\n" ); document.write( "In the end, Marek had 75% of the total number of coins the two friends had left.
\n" ); document.write( "
\n" ); document.write( "AN EASY WAY TO SOLVE IT (guess and check):
\n" ); document.write( "
\n" ); document.write( "Fist Guess:
\n" ); document.write( "What if Zaven initially had \"300coins\".
\n" ); document.write( "Then, Zaven must have spent \"200coins\" ,
\n" ); document.write( "and must have had left with \"300coins-200coins=100coins\" in the end.
\n" ); document.write( "Then, Marek
\n" ); document.write( "must have started with \"900coins-300coins=600coins\"
\n" ); document.write( "must have spent \"0.75%2A200coins=150coins\" ,
\n" ); document.write( "and have had left \"600coins-150coins=450coins\" in the end.
\n" ); document.write( "Then, Zaven and Marek then together had \"100coins%2B450coins=550coins\" in the end,
\n" ); document.write( "and that would mean that in the end,
\n" ); document.write( "the number of coins Marek had,
\n" ); document.write( "as a fraction and as a percentage of the number of coins Zaven and Marek had together, was
\n" ); document.write( "\"450coins%2F%22550+coins%22=9%2F11=%220.818181...%22=%2281.8181...%22\"\"%22%25%22\"
\n" ); document.write( "
\n" ); document.write( "We need \"75\"\"%22%25%22\" as an answer, so we should try to have Marek start with a little less with respect to Zaven.
\n" ); document.write( "
\n" ); document.write( "second Guess:
\n" ); document.write( "What if Zaven initially had \"360coins\".
\n" ); document.write( "Then, Zaven must have spent \"240coins\" ,
\n" ); document.write( "and must have had left with \"360coins-240coins=120coins\" in the end.
\n" ); document.write( "Then, Marek
\n" ); document.write( "must have started with \"900coins-360coins=540coins\"
\n" ); document.write( "must have spent \"0.75%2A240coins=180coins\" ,
\n" ); document.write( "and have had left \"540coins-180coins=360coins\" in the end.
\n" ); document.write( "Then, Zaven and Marek then together had \"120coins%2B360coins=480coins\" in the end,
\n" ); document.write( "and that would mean that in the end,
\n" ); document.write( "the number of coins Marek had,
\n" ); document.write( "as a fraction and as a percentage of the number of coins Zaven and Marek had together, was
\n" ); document.write( "\"360coins%2F%22480+coins%22=3%2F4=75%2F100=0.75=75%2F100=75\"\"%22%25%22\"
\n" ); document.write( "
\n" ); document.write( "A HYBRID OF THE SOLUTION ABOVE AND jogsarithmetic's solution:
\n" ); document.write( "Let's call the number of coins Zaven had at start, what he spent, and what he had left in the end 3x, 2x, and x, respectively.
\n" ); document.write( "
\n" ); document.write( "Then, we have just one variable, and the equation
\n" ); document.write( "\"%28900-4.5x%29%2F%28900-3.5x%29=0.75\"<-->\"900-4.5x=0.75%28900-3.5x%29\"<-->\"3600-18x=3%28900-3.5x%29\"<-->\"3600-18x=2700-10.5x\"<-->\"3600-2700=7.5x%29\"
\n" ); document.write( "\"x=900%2F7.5=120\"
\n" ); document.write( "In th e end, the number of coins Marek had was \"900-4.5%2A120=900-540=highlight%28360%29\"
\n" ); document.write( "
\n" ); document.write( "Some teachers want problems solved the way it was taught in class, and may not like alternative solutions.
\n" ); document.write( "Some teacher may want to give extra point f=if more that one way to solve the problem is shown.
\n" ); document.write( "
\n" );