A factory is to be built on a lot measuring 150 ft by 200 ft. A local building code specifies that a lawn of uniform width and equal in area to the factory must surround the factory.

21000

Step-by-step explanation:

Let x = the width of the lawn

Find the total area of the factory and the lawn: 200 * 210 = 42000 sq/ft

Factory area has to equal lawn area, therefore

21000 sq/ft = area of the lawn and the factory

The dimensions of the factory: (200-2x) by (210-2x)

Find x using the area of the factory

(200-2x) * ( 210-2x) = 21000

42000 - 420x - 400x + 4 = 21000

<=> - 205x + 5250 = 0

<=> (x-30)(x-175) = 0

<=> x= 30 or x=175 but x = 30 ft is the solution that makes sense for the width of the lawn, so

Thus we have the area of the factory using these dimensions:

150 * 140 = 21000

i believe the correct answer is b.