15. It is given that P and Q are supplementary which means that the sum of both the angles is 180 degrees so it follows:

Substitute the values given in the equation to get:

So the value of angle Q is:

Hence angle Q is 123 degrees.
17. It is given that J and K are complementary angles that means the sum is 90 degrees. It is also given that angle J is 18 less than K so it follows:

Therefore the measure of the angle J is:

Hence J is 36 and K is 54 degrees.