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 the number of days be x.
He saves $50-$15=$
<gadget id="calculator">50-15</gadget>
<output>35</output>
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.

<result>7</result>