A company is expanding its building area from 16,000 square feet to 19,360 square feet. What is the percentage increase of the area of the building space?

2.1%

21%

79%

33.6%

So assume that 16000=100% and 19360 is x%

%=parts out of 100 so

100%=100/100

16000=100%

since they should be the same

16000/100=19360/x

multiply both sides by x/19360 to clear fraction

16000x/1936000=1

simplify

x/121=1

multiply both sides by 121

x=121

19360 is 121%

the increase is 121-100=21% increase

the increase is 21%