Answer:
GIVEN : magnitude of angle B = 68°
magnitude of angle C = 70°
So the value of angle A (interior) be A
We know A + angle B + angle C = 180° [ Sum of all three interior angles of a triangle = 180°]
=> A + 68° + 70° = 180° [By linear equation we can find the value of A]
=> A + 138° = 180°
=> A = (180 - 138)°
=> A = 42°
A(interior) + A(exterior) = 180° [ Sum of all adjacent angle on a straight line =180°]
42° + A(exterior) = 180°
=> A(exterior) = (180-42)°
=> A(exterior) = 138°
As because A(exterior) = x = 138° (ans)
