Pikuai answers~
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To solve this it takes simple addition and subtraction. But, firstly you must realize the pattern. For 2 pies its 10, and for 3 pies it's 15. So, it adds 5 cups of apples per pie. 5+5=10 which is why 2 pies need 10 cups of apples. Now, we've identified the pattern ( 5 cups of apples per pie) you simply add 5 each time you go up a number.
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therefor the answer is 35 cups of apples for 9 pies!
I hope this helps! Have an amazing day~
