Ill give u $20 if u answer

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?

Bring the fraction a/a-4 to a denominator of 16-a^2