Answer:
see explanation
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Sum the 3 angles given and equate to 180
4x - 13 + 15 + x + 18 = 180 ( simplify left side )
5x + 20 = 180 ( subtract 20 from both sides )
5x = 160 ( divide both sides by 5 )
x = 32
∠A = 4x - 13 = (4 × 32) - 13 = 128 - 13 = 115°
∠C = x + 18 = 32 + 18 = 50°
As a check : 115° + 15° + 50° = 180° ← correct
