Provide two or three pots of flowers for every 100 sq ft of floor space under a ceiling of 8 ft. if your classroom has an 8-ft ceiling and measures 35 ft by 40 ft, how many pots should it have?

You need to calculate the square feet of the ceiling, so you multiply the dimensions of the ceiling. 

35(40)=1400ft^2 

now, you know that for every 100 square feet you need a specific # of pots, so you divide 1400 by 100. 
1400/100=14 
now we know that there are 14 areas of 100 where you can place 2-3 pots. 
so, you multiply 14 by 2 & by 3 

14(2)=28 
14(3)=42 

so you know that you can have between 28-42 pots.