Recall that complementary angles are those which added give 90 degrees (a right angle)
They tell us that the two angles m1 and m2 are complementary, so we know that their addition must equal 90
They aslso give us expressions for each in terms of x, and want us to give the measure of both angles.
So we start by saying:
m1 + m2 = 90
(3 x + 20) + (5 x + 30) = 90
simply by replacing each angle with its algebraic form.
Now we conbine like terms and work on solving for the unknown "x":
3 x + 5 x + 20 + 30 = 90
8 x + 50 = 90
8 x = 90 - 50
8 x = 40
x = 40/8
x = 5
So now we can answer what m1 is and what m2 is:
m1 = 3 x + 20 = 3 (5) + 20 = 35
m2 = 5 x + 30 = 5 (5) + 30 = 25 + 30 = 55
Then, m1 = 35 and m2 = 55.