The table above shows the percent of the area of a town devoted to three uses. If the area devoted to business use
is 7,200 acres less than the area devoted to residential
use, what is the area, in acres, devoted to government
use?
A) 1,400
B) 1,800
C) 5,200
D) 44,000

Explanation:

Let

r = area devoted to residential use

This variable is some positive real number, and it represents the area in acres.

Your teacher says that " the area devoted to business use is 7,200 acres less than the area devoted to residential use"

This means the expression r-7200 represents the area for business use

Note the jump from 25% to 65% is 65/25 = 2.6, meaning that we multiply by 2.6 when going from the business area to the residential area.

So we'll multiply by 2.6 to go from r-7200 to r

We'll have this equation

2.6(r-7200) = r

because it's effectively saying

2.6*(business area) = residential area

Let's isolate r

2.6(r-7200) = r

2.6r-2.6*7200 = r

2.6r - 18720 = r

2.6r - r = 18720

1.6r = 18720

r = 18720/(1.6)

r = 11700

We'll use 11700 acres for the residential portion.

And also r-7200 = 11700-7200 = 4500 acres are set aside for the business district.

The largest region (residential) uses 11700 acres of land.

Note the jump from 10% to 65% involves a multiplier of 6.5 because 65/10 = 6.5

So if g is the amount of government land used, then,

6.5g = r

6.5g = 11700

g = 11700/(6.5)

g = 1800

1800 acres of land are for government use

This is why the answer is choice B.