How to solve it with equations

Question

The gardening store sells clay flower pots, which hold 1 liter of dirt, and ceramic flower pots, which hold 5 liters. Matthew bought 27 flower pots, which will hold a total of 63 liters of dirt. How many of each type of flower pot did he buy?

Answer 1

Let x = the number of clay pots.  Since Matthew bought 27 pots in total, the number of ceramic pots he bought is 27-x.

 

63 liters =  (1 liter)*(x clay pots) + (5 liters)*(27-x ceramic pots)

 

63 = x + 135 - 5x

 

63 = 135 - 4x

 

Solve for x (clay pots), then 27-x (ceramic pots).