In this case the answer is very simple .
Step 01:
Data
ΔABC ≅ ΔDEF
Step 02:
Since both triangles are congruent we can say that,
∠A ≅ ∠D
( x + 30) = 80
x = 80 - 30 = 50
∠A = 50 + 30 = 80
The answer is:
∠A = 80 °
