does someone mind helping me with this problem? Thank you!

Step-by-step explanation:
∠A + ∠B + ∠C = 180°
Here the value of ∠B and C is given below...we need to find the value of ∠A ....
a + 120° + 40° = 180°
a + 160° = 180°
a = 160° - 180°
a = 20°
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