1) Let's draw a triangle do better understand this:
According to the Exterior Angle Theorem:
The measure of the exterior angle is equal to the sum of two non adjacent angles.
Since the exterior angle is equal to 68º, the sum of those is 68º. The other one (in red) is 180º-68º =112º
The remote interior angle, B
m∠d=m∠c+m∠b
68 = 112 +m∠b
m∠b=112-68
m∠b=44 then m∠a = 180 -(112+44) =24
2) Since the question is what could not be the measure
4) 71º
Because 180º - (112º+71º) = -3 False
