the complement of an angle is 90 minus the angle, or
90 - x = complement angle
if x is 18 more than 3 times it's complement, then
x = 3(complement angle) + 18
We can substitute "90 - x" for the "complement angle" in the second equation:
x = 3(90 - x) + 18
distribute the 3 to the 90 and the x
x = 270 - 3x + 18
add 3x to both sides
4x = 270 - 18
4x = 252
x = 63
the measure of angle x is 63 degrees
