Please help with #76 and #77. Practicing for AP exam.

76. To help restore a beach, sand is being added to the beach at a rate of s(t) = 65 + 24 sin (0.3t) tons per hour, where t is measured in hours since 5:00 A.M. How many tons of sand are added to the beach over the 3-hour period from 7:00 A.M. to 10:00 A.M.? (A) 255.368 (B) 225.271 (C) 85.123 (D) 10.388 X Graph of f 77. The graph of the function f is shown above. For what values of a does lim f (x) = 0