Respuesta :

AL2006
You solve it by adding up all 3 angles, and then writing

(the sum) = 180 degrees.

This equation is true in EVERY triangle.

Write it, and then solve it to find y .
The sum of the triangle is 180
180 = 40 + (y+30) + y
-40 -40
140 = (y+30) + y
140 = 2y + 30
-30 -30
110 = 2y
/2 /2
55 = y (40+55+85=180)