Im assuming the question is asking: if she collected $22 in sales tax what was the cost of the items her store sold. you should make sure you type the question correctly otherwise it'll be hard to answer.
going with my assumption of what the question is, we want to find the total cost of all items her story sold. let that cost be c. since there is 5% sales tax on everything and we know the sales tax is worth $22,m we have:
5%(c) = 22 dividing both sides by 5% (or .05) gives: c = $440
