Answer: 2.357hrs
Explanation:
Rate of dirt removal (rate) = 7/8 tons/hr
Total dirt removed (dirt) = 2 1/16 tons
Each hour, 7/8 tons of dirt will be removed, so if you work for h hours, you will have removed 7/8 * x tons of dirt. You can set up an equation as follows:
7/8 tons/hr * h hr = 2 1/16 tons (see how the units work out to give you tons)
Rearrange and solve for h:
h = (2 1/16) / (7/8) = 33/14 hrs = 2.357hrs