Question

the measure of one angle of a triangle is 70° and the measure of another angle is 40° find measure of the third angle

Answer 1

70+40+x=180
X=70
Hope it helps

Answer 2

Angle sum property of a triangle states that all the three angles sum up to 180 degrees

=> 70 + 40 +x = 180
let the unknown angle be x degrees

110+x = 180
x = 180 - 110
x = 70 degree
Therefore the third angles is 70 degrees 



Hope it helps!!
Cheers!!