360 - 90 = 270
Plug in the two expressions
270 = (7x + 6) + (6x - 7) -> expand
270 = 42x^2 - 1 -> bring the one to the other side and add
271 = 42x^2 -> divide by 42
6.4 = x^2 -> find the square root
2.5 = x
Then solve both equations with x = 2.5 :^)
Hope this helped!!
