Answer:
C. 75°
Step-by-step explanation:
the sum of interior angles of a triangle is 180°
that means:
∠A + ∠B + ∠C = 180°
3x + 60 + 5x = 180°
and now to find x:
3x + 60 + 5x = 180
3x + 5x = 180 - 60
8x = 120
x = 120/8
x = 15
so
∠A= 3 * 15 = 45°
∠B = 60°
∠C = 5 * 15 = 75°
the value of C:
5 * 15 = 75
