Which of the following is the equation of a direct variation that has a constant of variation equal to -1/2

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 2x^2+7x+4?

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4