Help!! Which is the correct answer?

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.

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

Find the quotient. 50a2 – 98b2 -5a +7b