show work, not excel

#94 You run a school in Florida. Fixed monthly cost is $6000 for rent and utilities, $5000 is spent in salaries and $1000 in insurance. Also every student adds up to $90 per month in stationary, food etc. You charge $700 per month from every student now. You are considering moving the school to another neighborhood where the rent and utilities will increase to $10000, salaries to $6000 and insurance to $2000 per month. Variable cost per student will increase up to $150 per month. However you can charge $1000 per student. At what point will you be indifferent between your current mode of operation and the new option? a) 30 b) 20 c) 25 d) 40