Find the nearest two positive co-terminal angles and nearest two negative co-terminal angles 5 pi / 2

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?

Multiplying fractions by whole number 5 x 1/3=?

A+b= 17, ab=70, find the value of |a-b|