A truck needs 7 gallons of fuel to travel 56 miles. Can the truck travel 48 miles with 6 gallons of fuel

All thing held equal, yes 6 gallons should work. The truck can travel 8 miles per gallon, or 7 gallons times 8 equals 56 miles. Now if there were variables such as traffic or hills or turning on the air conditioning, that could affect how many miles per gallon the truck gets.

56 divided by 7 = 8

48 divided by 6 = 8

8 = 8

since it is the same rate, then

Yes, the truck can travel 48 miles with 6 gallons of fuel