If one store sells 12 pens for $9.00 and another sells 10 pens for $7.80, which is the better deal?

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

When a rectangle is dilated, how do the perimeter and area of the rectangle change?

Which number completes the inequality? 2/3 < _ < 7/9