I don't know how to do this, I am not smart 100 x 900

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 of the following represents the zeros of f(x) = 6x3 − 31x2 + 4x + 5? −5, one third , one half 5, − one third , one half 5, one third , − one half 5, one third , one half

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)