Answer:

Explanation:
We know that A and B are complementary angles. So, they must add up to 90°. As an equation:

Since we know their equations, substitute:

Solve for x. Combine like terms on the left:

Subtract 9 from both sides:

Divide both sides by 9:

So, the value of x is 9.
We want to find A. So, let's use the equation for A:

Substitute 9 for x:

Add:

So, the measure of A is 17°.