Answer:
5
Step-by-step explanation:
As seen in the figure, we know that because ΔABC is isosceles, ∠B = ∠C, so we know that 75 = 3x, x = 15. Next, following the rule that all angles in a triangle sum to 180°, we can set up this equation and solve it:
4y + 10 + 75 + 75 = 180
4y = 180 - 160
y = 20
∴ y = 5
