Ella bought some key chains and spent a total of $40. Each key chain cost the same whole-dollar amount. She bought between 9 and 13 key chains. How many key chains did Ella buy?

Ineed to know the answer to this algebra question.

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

One file clerk can file 10 folders per minute. a second file clerk can file 11 folders per minute. how many minutes would the two clerks together take to file 672 folders?