Let's call the measure of the larger angle as x, and the measure of the smaller angle as y.
When two angles are complementary, their sum is equal to 90º, therefore
The larger of the two is 30° more than twice the smaller, writing this as an equation, we have
If we substitute this expression for x in the first equation, we have
Using this y-value on the first expression, we have
Then, the larger angle is 70º and the smaller angle is 20º.