Question 419862
Two angles are considered complements if their measurements add up to 90 degrees.  The sum of your two angles is 3x + 2x which must equal 90 for the angles to be complementary.

3x + 2x = 90
5x = 90 (combining like terms)
x = 18 (dividing both sides by 5)

The answer is x = 18.

Let's check the answer:  If x = 18, then the first angle has a measurement of 3x = 3 * 18 = 54; the second angle has a measurement of 2x = 2 * 18 = 36.  Since 54 + 36 = 90, the angles are complementary.