Question

do i add the numbers inside the triangle and then add the answer to 8x+15 and then subtract 180??

Answer 1

well this uses the exterior angle of a triangle

and the rule is: the sum opposite interior angles is equal to the exterior angle

so you have

3x + 20 + 4x + 5 = 8x + 15

which can be written, after collecting like terms as

7x + 25 = 8x + 15

now just solve for x.

hope it helps

Answer 2

close enough thx