The arc subtends an angle of 300° .
Explanation:
Radius = 75 cm
Arc length = 125π cm
Arc length = (θ/360) (2πr)
125π = (θ/360) (2π x 75)
125π = (θ/360) (150π)
125π/150π = (θ/360)
5/6 = (θ/360)
(5/6) (360) = θ
θ = 300°
The arc subtends an angle of 300° .