The outside angle of B needs to equal 180 - 79 = 101 degrees.
The 3 outside angles of a triangle need to equal 360 degrees.
Set up the equation with what we know:
X + (x+5) + 101 = 360
Simplify:
2x + 106 = 360
Subtract 106 from both sides:
2x = 254
Divide both sides by 2:
x = 254 / 2
x = 127