Angle 5x+7 is equal to the the sum of its remote interior angles, which we are given as x+15 and 6x-26. Therefore, 5x+7=x+15+6x-26. We will combine like terms to get 5x+7=7x-11. Move the 7x over to the other side by subtraction and the 7 to the other side by subtraction to get -2x = -18. That leaves us with an x value of 9. There you go!
