Answer
$(9x+6)^\circ=69^\circ$
$(3x)^\circ=21^\circ$
Work Step by Step
If two angles are complementary, the sum of the two angles is a right angle ($90^\circ$):
$(9x+6)^\circ+(3x)^\circ=(12x+6)^\circ=90^\circ$
$12x+6=90$
$12x=84$
$x=7$
$(9x+6)^\circ=69^\circ$
$(3x)^\circ=21^\circ$
