document.write( "Question 1062268: the sum of my parents' ages is 70. Twenty years ago, my father was 4 years older than my mother. how old are they now \n" ); document.write( "

Algebra.Com's Answer #677121 by Cromlix(4381) $\"\"$ $\"About$

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Hi there,
\n" ); document.write( "the sum of my parents' ages is 70
\n" ); document.write( "Father = x
\n" ); document.write( "Mother = y
\n" ); document.write( "x + y = 70........Eq(1)
\n" ); document.write( "x = 70 - y........Eq(1)
\n" ); document.write( "Twenty years ago, my father was 4 years
\n" ); document.write( "older than my mother.
\n" ); document.write( "x - 20 = 4 + (y - 20)........Eq(2)
\n" ); document.write( "Replace x in Eq(2) with 70 - y
\n" ); document.write( "(70 - y) - 20 = 4 + (y - 20)......Eq(2)
\n" ); document.write( "70 - y - 20 = 4 + y - 20
\n" ); document.write( "Collect like terms
\n" ); document.write( "- y - y = 4 - 20 + 20 - 70
\n" ); document.write( "-2y = -66
\n" ); document.write( "Multiply both sides by -1
\n" ); document.write( "2y = 66
\n" ); document.write( "y = 33
\n" ); document.write( "Substitute y = 33 into Eq(1)
\n" ); document.write( "x + y = 70.........(1)
\n" ); document.write( "x + 33 = 70
\n" ); document.write( "x = 70 - 33
\n" ); document.write( "x = 37
\n" ); document.write( "Mother is 33 years old
\n" ); document.write( "Father is 37 years old.
\n" ); document.write( "Hope this helps :-) \n" ); document.write( "

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