Answer:
3/2 gal = 1.5 gal
Step-by-step explanation:
The amount of gas used in a given time is found by multiplying the rate of gas usage by the time.
__
(60 mi/h) / (20 mi/gal) = 3 gal/h
We know that 30 minutes is 1/2 hour, so the usage in 1/2 hour is ...
(1/2 h) × (3 gal/h) = 3/2 gal = 1.5 gal