Answer:
∠C' = 66°
Step-by-step explanation:
Because triangles ABC and A'B'C' are similar, their angles are still the same; only their side lengths are different, though still proportionate.
Hence, ∠A = ∠A', ∠B = ∠B', and ∠C = ∠C'.
Here, we're given that ∠A = 68, which means ∠A' = 68; we also know that ∠B = 46, so ∠B' = 46.
We want to find C', so remember that all angles in a triangle sum to 180:
∠A' + ∠B' + ∠C' = 180
68 + 46 + ∠C' = 180
114 + ∠C' = 180
∠C' = 66°