Ben starts each day with $50, spends $15 every day and saves the rest. After a few days, his mom doubled his total savings and his dad gave him an additional $10. If he now has $500, How many days have elapsed?
Let's be accurate as possible and think first.
7
Let the number of days be x.

He saves $50 - $15 = $35 each day.

After x days he had saved $35 * x = $35x.

His mom doubled his savings to give $35x * 2 = $70x.

His dad added $10 to give $70x + $10 = $500.

Subtracting 10 from both sides of the equation formed gives $70x = 490.

Dividing both sides by $70 give x = 7 days.

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Therefore, the answer is 7