Question

3 angles of a triangle have measure 80°,70°and y.Find the value of y.

Answer 1

we know that 
in triangle
a+b+c=180(sum of angle in triangle is 180)
80+70+y=180
150+y=180
y=30
so,
value of y is 30 degree

Answer 2

Let third angle be y
80°+70°+y=180°{anglesum property of a triangle}
150°+y=180°
y=30°
Ans 3rd angle =30°