V = 4πr³/3
Substituting,
V = (4/3)π(3 cm)³
V = 36π cm³
The answer is 59. First you multiply 4 by 5 (20), then subtract 20 from 79 (59).
If the variable is the same you can combine it
The cost would be $4.74. 3.95 times 0.2 is 0.79. Add that to 3.95 and get 4.47