Question

The landscaper pours 200 gallons of herbicide in a pond. The herbicide degrades 10% each week. How much will be in the pond after 1 week?

Answer 1

180 gallons

Explanation:

200 gal

10% = .10

200 x .10 = 20

200 - 20 = 180

Answer 2

180 gallons

Explanation:

In order to calculate you just need to calculate the 10% of the herbicide that is being degraded in the first week, so we do a rule of three to calculate that 10%:

`(200)/(100) =(x)/(10)\\ x=10*(200)/(100) \\x=20`

So the 10% is 20 gallons, and that is the gallons of herbicide that degraded in the first week, so we just withdraw the 20 gallons degraded from the initial 200 gallons:

200-20=180

So there will still be 180 gallons in the pond after one week.