Since (x, y) ⟶ (ax, ay) and (4.3, 2.9) ⟶ (8.6, 5.8)
By comparison x = 4.3, y = 2.9 and ax = 8.6, ay = 5.8
Therefore: a = ax / x , 8.6 / 4.3 = 2.
a is also = ay / y = 5.8 / 2.9 = 2.
In both cases a = 2, though we didn't need both cases, one was enough.
a = 2