As the total amount of dirt is in pound , so first we need to express 1.4 ton in pounds.
Now, 1 ton= 2,000 pounds
So, 1.4 ton= (2000×1.4)=2,800 pounds
The truck can carry 2,800 pounds of dirt at one time and it need to carry total 11,200 pounds of dirt.
So, the number of trips it must take= (Total amount )/(Amount in each trip)
= [tex] \frac{11,200}{2,800} [/tex]
= 4