let's recall that in an isosceles triangle, the twin sides make twin angles at the bottom/base, so on the triangle on the left-side, if the "vertex" atop has an angle of 116°, then the twin sides below are simply 180° - 116 = 64, split that in half and that's 32° each.
The same is true for the isosceles triangle on the right side. Also recall that a flat-line is always 180°, 32 + 72 + 76 = 180.
Check the picture below.
