I always love helping students cheat so
since supplementary means 'adds to 180*',
and you know one angle is 45*,
x + 45* = 180
180 - 45 = x
x = 135*
since supplementary means 'adds to 180*',
and you know one angle is 45*,
x + 45* = 180
180 - 45 = x
x = 135*