Hello!
First you have to find out how far the car goes on 1 gallon of gas
To find this you do the distance traveled divided by the amount of gas used
25/4 = 6.25
Next you do the amount of distance the car needs to travel divided by the distance the car goes on 1 gallon of gas
125/6.25 = 20
The car needs 20 gallons of gas to go 125 miles
The answer is 20 gallons
Hope this helps!