Let's define variables:
x1: gear 1
x2: gear 2
The relationship between gears is:
x1 / x2 = (1 1/2) / (1/2)
Rewriting:
x1 / x2 = (3/2) / (1/2)
x1 / x2 = (3 * (1/2)) / (1/2)
x1 / x2 = 3
Another unit rate is:
x2 / x1 = (1/2) / (1 1/2)
x2 / x1 = (1/2) / (3/2)
x2 / x1 = (1/2) / (3 * (1/2))
x2 / x1 = 1/3
Answer:
two unit rates to represent the gear ratio are:
x1 / x2 = 3
x2 / x1 = 1/3