document.write( "Question 4440: John is 7 yrs older than Peter. If 13 is added to john's age and 5 is subtracted from Peter's age John will be twice as old as Peter. Find their age.
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Algebra.Com's Answer #2950 by guapa(62)\"\" \"About 
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Let x represent Peter's age. Then x+7 is John's age
\n" ); document.write( "x = x+7 (First equation)
\n" ); document.write( "Next it says if 13 is added to John's age : x+7+13
\n" ); document.write( "5 is substracted from Peter's age: x-5
\n" ); document.write( "Let's set up the equation so far:
\n" ); document.write( "Peter's age = John's age
\n" ); document.write( " x-5 = x+7+13 And it says that under these conditions John will be twice as old as Peter:
\n" ); document.write( "2*Peter's age = John's age
\n" ); document.write( "2(x-5)= x+7+13 (second equation)
\n" ); document.write( "2(x-5)= x+20 Now let's simplify the left side
\n" ); document.write( "2x-10= x+20 Add 10 to both sides
\n" ); document.write( "2x-10+10 = x+20+10
\n" ); document.write( "2x = x+30 Substract x from both sides
\n" ); document.write( "2x-x = x+30-x
\n" ); document.write( "x = 30
\n" ); document.write( "Therefore,
\n" ); document.write( "x+7 = 30+7 = 37
\n" ); document.write( "So, Peter's age is 30 and John's age is 37.
\n" ); document.write( "Let's check it by substituting the variables of the second equation.
\n" ); document.write( "2(30-5) = 30+7+13
\n" ); document.write( "2(25) = 50
\n" ); document.write( "50 = 50
\n" ); document.write( "I hope this helps.
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