Question 1007572
Let their ages NOW be f and s.  So we have
f = 5s   and in 18 years
f+18 = 2(s+18)
f+18 = 2s + 36
f = 2s + 18
Now substitute the first into this second one and get
5s = 2s + 18
3s = 18
s = 6 years old
f is then 30 years old