I need help with math pls.

Question

The gardening store sells clay flower pots, which hold 9 liters of dirt, and ceramic flower pots, which hold 1 liter. Caleb bought 4 flower pots, which will hold a total of 20 liters of dirt. How many of each type of flower pot did he buy?

Answer 1

Our equations are:

a is clay, b is ceramic

9a + b = 20

a + b = 4

We can subtract the second from the first to get:

8a = 16 -> a = 2

recall: a + b = 2 so

-> b = 2

So he bought 2 clay pots and 2 ceramic pots.