Answer:
[tex]x=27[/tex]
Step-by-step explanation:
we know that
[tex](3x+9)^o+90^o=180^o[/tex] ----> by supplementary angles (form a linear pair)
Solve for x
Combine like terms
[tex](3x+99)^o=180^o[/tex]
subtract 99 both sides
[tex]3x=180-99\\3x=81[/tex]
Divide by 3 both sides
[tex]x=27[/tex]
