Since the angles are supplementary, we know that they must add up to equal 180 degrees by the definition of supplementary angles
set the sum of the 2 angles to equal 180 and solve for x
6x + 48 + 60 = 180 6x + 108 = 180 6x = 72 x = 12
you could check to make sure that your x value is correct by plugging it back into the equation 6(12) + 48 + 60 = 180 72 + 48 + 60 = 180 120 + 60 = 180 180= 180
