Find all the linear factors

f(x) =3x^4-7x^3-10x^2+28x-8

Factor the expression using gcf 9b+45

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

A50% increase followed by 33 1/2% decrease