Sides AC and CB are identical, which mean the two bottom angles are also identical.
Angle B (2x) would equal 50.
The three inside angles of a triangle equal 180, so the top angle would equal 180 - 50-50 = 80.
Now set the equation for angle C to equal 80 and solve for Y.
5y+10 = 80
Subtract 10 from each side:
5y = 70
Divide both sides by 5:
y = 70/5
y = 14
