document.write( "Question 265919: From a group of green monkeys, 10 females leave. At this point there are 3 males for every female. Then 25 males leave, at which point there are two males for every female. How many females were there originally? \n" ); document.write( "
Algebra.Com's Answer #195476 by ptaylor(2198)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "Let x=number of female green monkeys in the original group
\n" ); document.write( "And let y=number of male green monkeys in the original group
\n" ); document.write( "Then (x+y)=total number of monkeys in the original group\r
\n" ); document.write( "\n" ); document.write( "When 10 female green monkeys leave, we have left (x-10)+y monkeys remaining and we are basically told that 3/4 of this number are males, so:
\n" ); document.write( "(3/4)((x-10)+y)=y multiply each side by 4
\n" ); document.write( "3((x-10)+y)=4y get rid of parens
\n" ); document.write( "3x-30+3y=4y subtract 4y and add 30 to each side
\n" ); document.write( "3x-30+30+3y-4y=4y-4y+30 collect like terms\r
\n" ); document.write( "\n" ); document.write( "3x-y=30-----------------------------------------eq1\r
\n" ); document.write( "\n" ); document.write( "When 25 males leave, we have left(x-10)+(y-25) or (x+y-35) monkeys remaining and we are told that 2/3 of this number are males, so:
\n" ); document.write( "(2/3)(x+y-35)=(y-25) multiply each side by 3
\n" ); document.write( "2(x+y-35)=3(y-25) get rid of parens
\n" ); document.write( "2x+2y-70=3y-75 subtract 3y and add 70 to each side
\n" ); document.write( "2x+2y-70+70-3y=3y-3y-75+70 collect like terms\r
\n" ); document.write( "\n" ); document.write( "2x-y=-5----------------------------------------eq2\r
\n" ); document.write( "\n" ); document.write( "subtract eq2 from eq1 and we get
\n" ); document.write( "x=35------------------------------number of females originally
\n" ); document.write( "substitute x=35 into eq 1 and we get:
\n" ); document.write( "3*35-y=30
\n" ); document.write( "105-y=30
\n" ); document.write( "-y=-105+30=-75
\n" ); document.write( "y=75 number of males originally\r
\n" ); document.write( "\n" ); document.write( "CK
\n" ); document.write( "10 females leave:
\n" ); document.write( "Number of females remaining:35-10=25
\n" ); document.write( "Number of males: 75
\n" ); document.write( "Total number of monkeys: 75+25=100
\n" ); document.write( "75/100=3/4
\n" ); document.write( "3/4=3/4
\n" ); document.write( "25 males leave:
\n" ); document.write( "Number of females remaining=25
\n" ); document.write( "Number of males=75-25=50
\n" ); document.write( "Total number of monkeys=50+25=75
\n" ); document.write( "50/75=2/3
\n" ); document.write( "2/3=2/3\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor
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