Question

For how many weeks would the class need to sell cookies in order to earn $5000.

Fyi: If in 3 weeks profit is $500.

Answer 1

The answer is 30 weeks.
To find this, first divide $500 and 3, giving you the answer of 166.666667. Round it up to the nearest hundredth, which would be 166.67. 
$166.67 per week.
Then divide 5000 and 166.67 which gives you 29.9994. Round up to  the nearest whole and your answer would be 30. It would take 30 weeks.