Solve for y
Equilateral triangles have all equal sides and angles.
180 deg is in one triangle and divide it among the 3 sides and you get 60 deg.
This is an equilateral triangle because all the sides are the same. The angle measures are 60.
\(5y+10=60, 5y=50, y=10\) so y is 10 degrees.
Notice we didn't even use x.
You are very welcome!