Answer:
down 7 1/4 feet
Step-by-step explanation:
4 1/2 + 2 3/4 = 4 2/4 + 2 3/4 = (4+2) +(2/4 +3/4) = 6 +5/4 = 7 1/4
The dolphin is 7 1/4 feet below the surface.
10r + 12