The sum of the measures of angles 2 and 3 is equal to the measure of ? .

Answer:
∠1
Step-by-step explanation:
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠1 is an exterior angle and ∠' s 2 and 3 are the opposite interior angles.
Hence
∠2 + ∠3 = ∠1