Answer:
The gear ratio is 2.5 :1.
Step-by-step explanation:
A gear ratio is the ratio of the teeth on the front sprocket and the teeth on the rear sprocket.
Given is that the bike has 45 front teeth and 18 rear sprocket teeth.
So, gear ratio will be [tex]\frac{45}{18}= \frac{5}{2}=2.5[/tex]
Hence, the ratio is 2.5 :1.