Can someone please give me the answers I will mark you brilliant as soon as it pops up

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?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry