Question

Today Angela's cat's age in months is the same as Angela's age in years. In one year her cat's age in months will be 2 times Angela's age in years. Today Angela is ? years old.

Answer 1

c = a
c+12 = 2(a+1)

c+12 = 2c+2
c = 10

so, the cat is 10 months old, Angela is 10 years old
next year,
cat is 22 months old, Angela is 11 years old
22 = 2*11

In this problem, you have to be careful to use different kinds of addition for c and a, since c is months and a is years.