For how many weeks would the class need to have car washes to earn $5000.

fyi : if for 4 weeks profit is $700

The correct answer would be for 29 weeks.
Its because if for 4 weeks the profit is $700, divide 700 and 4 which gives you $175 per week. Then divide 5000 and 175 which gives you 28.5714286. So all you have to do is round it up to the nearest whole which gives you the 29 weeks.
Hope that helps. :)