I need to know how much would 1200 square feet , 1600 square feet, 900 square feet cost per year from the 40,000 need to know what each dept would cost per year.

You will have to get the square feet of the various departments in a percentage. So divide 1200 square feet by 5,000 square feet. Now divide 1,600 square feet by 5,000 square feet. Finally divide 900 square feet by 5,000 square feet.

Now to get your costs take the $40,000 times the percentages calculated above to get your individual department cost per square feet per year.

$40,000 a year divided by 5000 square feet comes to $8 a square foot. If the landlord is willing to rent only 1200 square feet at the same rate then 1200 square feet x $8 = $9600, 1600 square feet is $12,800, and 900 square feet is $7200. I suggest taking $5 of that $40,000 and invest in a calculator.