2x =50 since it is an isosceles triangle
x =25
the sum of all angles in a triangle is 180
5y + 10 + 50 + 2x=180
5y + 10 + 50 +50 =180 because 2x = 50
combine like terms
5y +110 = 180
subtract 110 from each side
5y = 70
y = 14
the anwser to this is y=14
So you have to put 25 inside the blank box.
look at the attached picture
Hope it will help you
Good luck on your assignment