Question

Evie and her father are comparing their ages. At the current time, Evie's father is 36 years older than her. Theee years from now, Evie's father will be five times her age at that point. How old is Evie now?

Answer 1

Let F be the father's current age, and E be Evie's current age.
F = E + 36                 this is the current relation between the ages
F + 3 = 5(E + 3)        this the relationship in 3 year (hence the + 3)
Then solve by substituting one equation into another:
(E + 36) + 3 = 5(E + 3)
         E + 39 =  5E + 15
                24 = 4E
                  6 = E
Evie's current age is 6.