Answer:
A) 40
Explanation:
The angle adjacent 40 is complementary to it, meaning that it must have a measure of 90-40=50 degrees. This angle is a vertical angle with the one inside the triangle, meaning that it also has an angle of 50 degrees. Now that you know two of the angles in the triangle and you know that all of the interior angles of a triangle add up to 180 degrees, you can find angle 1:
![\angle 1=180-90-50=40^(\circ)](https://img.qammunity.org/2021/formulas/mathematics/high-school/5xqs88yce5qsza4csfq1kq36ith63ol2ka.png)
Hope this helps!