let

x = Justin's age now

y = Ethan's age now

Justin is two years older than Ethan:

x = y + 2

three years ago the sum of their ages was 30:

(x - 3) + (y - 3) = 30

by solving the system of equations:

x = y + 2

(x - 3) + (y - 3) = 30

we find:

x = 19 years

y = 17 years

click here to see the step by step solution of the system of equations:

Justin is 19 years old now.

Ethan is 17 years old now.