Hi there!
Let's use x as our variable. We know that complementary angles add up to 90 degrees. So, angle 1 is equal to x. Then, we can figure out that angle 2 is equal to 2x - 15. Then, to solve for x, we need to set the value of angle 1 plug angle 2 equal to 90, since the angles are complementary.
WORK:
x + 2x - 15 = 90
3x - 15 = 90
3x = 105
x = 35
ANSWER:
x = 35
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!