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.
