Bill had $21 to spend on four avocados.
after buying them he had $13. how
much did each avocado cost?

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?

Divide. write in simplest form 41/6 divided by 10

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible