Question
Mark folded 15 paper aeroplanes on the first day. Each day he did 10 more paper aeroplanes than the previous day. On the last day, he made 85 aeroplanes. How many days did he fold paper aeroplanes?
2 m

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Mark folded 15 paper aeroplanes on the first day. Each day he did 10 more paper aeroplanes than the previous day. On the last day, he made 85 aeroplanes. How many days did he fold paper aeroplanes?