You work as a grounds keeper for a small local elementary school and must fertilize the grass on the entire campus. you know that 4 containers cover 60 square yards. if the campus has 2,000 square yards of grass area, how many containers of fertilizer will you need?

This is a rule of three problem.
We'll need 4 containers of fertilizer to fertilize 60 square yards:
4 --------> 60
How many containers will we need to fertilize 2000 square yards?
Let x be the number of containers we'll need:
x --------> 2000

Now we can establish a rule of three with those two equation and solve for x to get the number of containers we'll need:





We can conclude that we'll need 133.33 containers of grass fertilizer to fertilize the 2000 square yards of grass of the campus.