Can someone answer. there is one question. there's a picture. you!

The number of revolutions of two pulleys is inversely proportional to their diameters. if a 24-inch diameter pulley making 400 revolutions per minute is belted to an 8-inch diameter pulley, find the number of revolutions per minute of the smaller pulley.

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

Average acceleration: i have no idea how to do this.