Let's assume
x represent the number of trips that the larger truck makes
so, we are given
If the smaller truck makes 18 more trips than the larger
so,
number of trips for larger truck =x
number of trips for smaller truck =x+18
The capacities of two trucks are 3 tons and 4 tons respectively
so, capacity of smaller truck per trip =3 tons / trip
total ton carried by smaller truck = (number of trips for smaller truck)*(capacity of smaller truck per trip)
now, we can plug values
total ton carried by smaller truck =3*(x+18)
total ton carried by larger truck = (number of trips for larger truck)*(capacity of larger truck per trip)
total ton carried by larger truck =4x
it can deliver 12 more tons of freight than the larger
so, we get
we can move 4x on left side
we get
...............Answer