Which angle would be complementary to

Hey bakery display easter cookies equally on seven trays if there are 567 cookies how many cookies are on each tray

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?

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?