Answer:
x = 15
Step-by-step explanation:
[tex]\text{If}\ \angle1\ \text{and}\ \angle2\ \text{are complementary, then}\ \angle1+\angle2=90^o.\\\\\text{We have:}\\\\\angle1=x^o\\\angle2=(3x+30)^o\\\\\text{Substitute:}\\\\x+(3x+30)=90\\\\(x+3x)+30=90\qquad\text{subtract 30 from both sides}\\\\4x=60\qquad\text{divide both sides by 4}\\\\x=15[/tex]
