What are some connections between geoimetric shapes and music?

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?

Answer for 10 points show work you guys in advanced < 3

Simplify this expression. 8x 16(x + y)