Question 1152205
let j = Jane's present age
let a = Amy's present age
:
Write an equation for each statement
:
Jane is seven years older than Amy.
j = a + 7
or
a = j - 7
:
Twelve years ago, Amy was half as old as Jane is now.
a - 12 = {{{1/2}}}(j)
get rid of the fraction, mult by 2
2(a-12) = j
2a - 24 = j
replace a with (j-7) from the 1st equation
2(j-7) - 24 = j
2j - 14 - 24 = j
2j - j = 38
j = 38 yrs old is Jane now
:
:
Check this:
 a = 38 - 7
 a = 31
"Twelve years ago, Amy was half as old as Jane is now."
31 - 12 = {{{1/2}}}(38)
19 = 19