Pet store A offered discount on pet food every 3 months. Pet store B offers a discount on pet food every 5 months. Both pet store are offering a discount on pet food this month. In how many months will both pet store offer their discount on pet food in the same month?

If you were to make a table it would be like this

A. 1. 2. * 3*. 4. 5. * 6*. 7. 8. * 9*. 10. 11. * 12*. 13. 14. * 15*.

B. 1. 2. 3. 4. * 5*. 6. 7. 8. 9. * 10*. 11. 12. 13. 14. * 15*.

The numbers with stars by them are the month in which the pet store had their discount. So as you can see both stores has a sale in month 15. It took store A 5 sales, and store B 3 sales to have matching sale months