Answer:
C
Step-by-step explanation:
The balloon has a volume
dependent on its radius
:

Differentiating with respect to time
gives

If the volume is increasing at a rate of 10 cubic m/s, then at the moment the radius is 3 m, it is increasing at a rate of

The surface area of the balloon is

and differentiating gives

so that at the moment the radius is 3 m, its area is increasing at a rate of

Answer:
2x+6=20
Step-by-step explanation:
She can make 12 scarves if the area of each scarf is 4 square feet.