Christen sells boxes of cookies for $4 each. rafael sells boxes of cookies for $7 each. each of them sold the same dollar amount. it was the smallest dollar amount for which this was possible. what was the dollar amount each of them sold? how many boxes did christen sell?

28 dollars, Christen sell 7 boxes and Rafael sell 4 boxes.

Step-by-step explanation:

We can make a list to see the rate of amount and dollars they got:

Boxes:     1,    2,  3,  4,   5,    6,    7,   8

Christen: 4,   8, 12, 16, 20, 24, 28, 32  ($)

Rafael:     7, 14,  21, 28, 35, 42, 49, 56 ($)

So the first one in common is 28 dollars, and just match them to the boxes, that's it.