Question

Man how do i do this

Answer 1

7x+18+90+51= 180
7x+159=180
7x=180-159
7x=21
X=21/7
X=3

7(3)+18=
21+18=
39°

Then check by adding 90°+51°+39°=180
Since that adds up to 180° x=3

Answer 2

the answer is x=3!!!!!!!!!!!!!!