Find the volume of the prism or pyramid below

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

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?

How do you determine if an ordered pair is a solution to a given equation?