<span>He has 45 dollars. He needs 315 dollars in order for him to have 315 dollars he would to need to save what? Then take 315-45= 270 dollars. Therefore he would need to save 270 dollars.
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To find the answer, you need to find the LCM of 3 and 5. It's 15, meaning that every 15 days, you will have both lessons on the same day. Have an awesome day! :)