Let J represent Justin's age, and let E represent Ethan's age.

Justin is 2 years older than Ethan, so J = E + 2.

In 9 years, or when Justin is J+9 and Ethan is E+9, the sum of their ages will be 30, so J + 9 + E + 9 = 30.

Simplify this last equation to:

J + E = 12

And now substitute our first equation for J, which gets rid of J so we can find E:

J + E = 12 -> (E + 2) + E = 12 or 2E = 10 or E = 5.

Plugging this in to our first equation to find J, we have:

J = E + 2 -> J = 5 + 2 = 7

so J = 7 and E = 5.