So let's call the missing angles A, B, and C. We know that A + B + C = 180 and we also know that A = B and that C = A + B - 40. So our equation looks like this
180 = 4A - 40 and we add 40 on both sides of the equal sign and get
220 = 4A and we divide on both sides of the equal sign by 4 to get
55 = A So that means B = 55 as well. That means 55 + 55 = 110 and 110 - 40 = 70 So C = 70 and to check, 55 + 55 + 70 = 180.
The measures of the three angles are; 55 degrees, 55 degrees, and 70 degrees.
