Vertically opposite angles of A is the alternate angles of angle of B
⇒ Angle A = Angle B
10x + 24 = 6x + 72 | Angle A = Angle B
10x - 6x = 72 -24 | subtract 6x -24 on both sides
4x = 48 | Combine like terms
x = 12 | Divide by 4
Angle A = 10x + 24
Angle A = 10(12) + 24
Angle A = 120 + 24
Angle A = 144°
Answer: Angle A = 144°