For any triangle, the three angles always add to 180
(y+10)+(2y)+(50) = 180
3y+60 = 180 ... combine like terms
3y+60-60 = 180-60 ... subtract 60 from both sides
3y = 120
3y/3 = 120/3 .... divide both sides by 3
y = 40
5.7m questions
7.4m answers