Answer:
B =48
Step-by-step explanation:
To solve this problem we need to know that ALWAYS the sum of complementary angles are equeal to 90.
If A is complementary to angle B, we can affirm that:
A+B=90.
Given that A=42, solving for B:
B = 90 - A = 90 - 42 = 48
Then, the measure of angle B is 48.