Mr. Nguyen had 5/8 of a gallon of gasoline. He used 1/2 of a gallon in his lawn mower. How much gasoline does Mr. Nguyen has left?

A.
4/8 of a gallon
B.
1/8 of a gallon
C.
1/6 of a gallon
D.
4/6 of a gallon

The volume of a spherical hot air balloon v(r) = 4 3 ? r3 changes as its radius changes. the radius is a function of time given by r(t) = 3t. find the instantaneous rate of change of the volume with respect to t at t = 2.