Answer:
131°
Explanation:
Supplementary angles add up to 180°.
We can write the following equation based on above mentioned information to first find the value of x then measure of ∠A:
3x - 28 + x - 4 = 180
4x - 32 = 180
4x = 212
x = 53
To find m∠A, replace x with the value we just found.
3×53 - 28 = 131°