We know that ∠1 and ∠2 are complementary, therefore, the sum of their measures is 90^(∘).
m∠1 + m∠2 = 90^(∘)
We are told that the measure of ∠1 is 42^(∘) and the measure of ∠2 is (3x)^(∘). Now we can substitute these values into the above equation and solve for x. We will ignore the symbol ^(∘) to make easier the calculations.
