You have the following information:
- Alonzo drove 380 miles using 14 gallons of gas
In order to determine how many gallons of gas would Alonzo need to drive 418 miles, you consider that each 380 miles are equivalent to 14 gallons of gas.
Then, you can use the following rule of three:
380/14 = 418/x
where x is the unknown amount of gallons of gas Alonzo needs. The rate must be equal because Alonzo drives with constant speed.
Then, you solve the previous equation for x, just as follow:
380/14 = 418/x multiply both sides by x
(380/14)x = 418 multiply by 14 and divide between 380 both sides
x = 418(14/380) simplify
x = 15.4
Hence, Alonzo would need 15.4 gallons of gas to drive 418 miles