A scalene triangle is a triangle with 3 angles, all of different measures.
All triangles have angles that add up to 180º.
If two of the angles are 47º and 72º, just add these together and subtract the sum from 180º and that's the measure of the third angle.
47 + 72 = 119
180 - 119 = 61
So the measure of the third angle is 61º.
