donna is 10 years older than her cousin Katie. The sum of their ages is 64. How old is each cousin?

Question

I need an equation to go along with this question to solve it. 

Answer 1

Donna is x years old

Katie  x-10 years old

x+x-10=64

2x=74

x=37

Donna is 37 years old  and

Katie is 27 years old.