Two angle add up to be complementary if one angle is 15 degree more than 2 times the other find the value of the smaller side

Let x and y represent the two angles.
.. x + y = 90 . . . . . . two angles are complementary
.. x -2y = 15 . . . . . . one angle is 15 more than twice the other (y = smaller angle)

Subtract the second equation from the first.
.. (x +y) -(x -2y) = (90) -(15)
.. 3y = 75
.. y = 25

The smaller angle is 25 degrees.