How much work is done lifting a 10 pound calculus book from the ground to the top of a 30 foot building with a cable which weighs 2 pounds per foot?

1200 ft·lb

Step-by-step explanation:

On average, you're lifting the 60-lb cable a distance of 15 ft, so doing 900 ft·lb of work. Lifting the 10-lb calculus book 30 ft requires 300 ft·lb of work.

The total work is 900 ft·lb + 300 ft·lb = 1200 ft·lb.