Rupert fish sells average fish for $ 12.00 which it purchases from various individuals for $ 5.00 each. Rupert fish has to pay $ 1,000.00 for rent every month, utilities of $ $500.00 and salary of $ 12,000 every month. The income tax rate is 10%.

1. How many fish does Rupert fish need to sell to breakeven per month?
2. How many fish does Rupert fish needs to sell to get the monthly net income after tax of $ 5,000
3. How much fish does Rupert fish needs to sell to get after tax net income of $ 4,900

Please give the detailed explanation