What could be a common denominator for 1 1/2 and 3/4

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.

What are the soultion(s) to the quadratic equation 40- x^2=0

If a baby uses 15 diapers in 2 days, how many diapers will the baby use in a year?