Slope - 9; through (6,-9)

What is the area of the trapezoid shown ?

Ill mark the brainliest if you me with the these three questions 7,8,9

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?