The value of x is 9
The value of x can be found using the exterior angle theorem. The exterior angle theorem states that the measure of an exterior angle in a triangle is equal to the sum of the measures of the two opposite interior angles. Here, the exterior angle is (5x+7) and two remote interior angles are (x+15) and (6x-26). So,
5x+7= (6x-26)+(x+15)
5x+7= 7x-11
11+7=7x-5x
18=2x
x=18/2
x=9
Therefore, the value of x is 9.