Step-by-step explanation:
for x = 2
a = 500 × (3/5)²
for x = 4
b = 500 × (3/5)⁴ = 500×(3/5)²×(3/5)²
so,
a/b = (500 × (3/5)²) / (500 × (3/5)² × (3/5)²) =
= 1/(3/5)² = 1/(9/25) = 25/9 = 2.777777778...
