document.write( "Question 234752: if john is twice as old as his son in 20 years the ratio of their ages will be 4:3 what is Johns sons current age? \n" ); document.write( "

Algebra.Com's Answer #173084 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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If john is twice as old as his son in 20 years the ratio of their ages will be 4:3,
\n" ); document.write( " what is John's son's current age?
\n" ); document.write( ":
\n" ); document.write( "let j = John's current age
\n" ); document.write( "Let s = Son's current age
\n" ); document.write( ":
\n" ); document.write( " $\"%28j%2B20%29%2F%28s%2B20%29\"$ = $\"4%2F3\"$
\n" ); document.write( "Cross multiply
\n" ); document.write( "3(j+20) = 4(s+20)
\n" ); document.write( "3j + 60 = 4s + 80
\n" ); document.write( "3j = 4s + 80 - 60
\n" ); document.write( "3j = 4s + 20
\n" ); document.write( ":
\n" ); document.write( "It said,\"John is twice as old as his son\"
\n" ); document.write( "j = 2s
\n" ); document.write( "Substitute 2s of j in the above equation
\n" ); document.write( "3(2s) = 4s + 20
\n" ); document.write( "6s = 4s + 20
\n" ); document.write( "6s - 4s = 20
\n" ); document.write( "2s = 20
\n" ); document.write( "s = 10 yrs is son's current age
\n" ); document.write( "then
\n" ); document.write( "2(10) = 20 yrs is John's present age
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check solution in 20 yrs
\n" ); document.write( "40/30 = 4/3 \n" ); document.write( "

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