Ok so you have a right angle and you know it had to equal 90°
So it gives you one of the angle measurments which is 49°
How i figured it out I subtracted 90 and 49 and got 41
Then I subtracted 41- 3 because on the second part of the angle in parenthesis i saw (x+3)
So 41 - 3 is 38
(38+3)+49= 90°