Question 1069073
 Sandy is 7 years younger than Mandy,
s = m - 7
 in 4 years time sandy will be half Mandy's age.
s + 4 = {{{1/2}}}(m + 4)
get rid of the fraction, multiply both sides by 2
2(s + 4) = m + 4
2s + 8 = m + 4
2s = m + 4 - 8
2s = m - 4
replace s with (m-7), from the first statement
2(m-7) = m - 4
2m - 14 = m - 4
2m - m = -4 + 14
m = 10 yrs is Mandy's age
:
 What are their ages presently 
I'll let you find Sandy's age, check the solutions in the 2nd statement