in the complementary angle, the sum of the angle is 90 degree
and in the supplementary angle, the sum of the angle is 180 degree
for complementary angle
42 + x = 90
x = 90 - 42
x = 48
so 48 is the complementary angle
for supplementary angle
42 + x = 180
x = 180 - 42
x = 138
so the supplementary angle is 138 .