Answer:
Third choice, 147
Step-by-step explanation:
Look at the bottom right angle, a straight line is 180 degrees, the line separating going on the line is at a 90 degree angle as there's a square that represents a right angle for the outer angle, the inner angle is also 90 as 90+90=180. A triangle is 180 degrees, all the equations plus 90 equals 180 so:
8x + 1 + 5x - 2 + 90 = 180
add like terms
13x + 89 = 180
subtract 89 from both sides
13x = 91
divide by 13
x = 7
Replace the equation the x in 5x - 2 to find angle 1, a straight line is 180 degrees so:
5x - 2 + ∠1 = 180
5(7) - 2 + ∠1 = 180
35 - 2 + ∠1 = 180
33 + ∠1 = 180
subtract 33 from both sides
∠1 = 147
