The table below shows the rates of charges for water consumption in a month.

First 20 m$^3$	$1.50 per m$^3$
Additional amount above 20 m$^3$	$2.00 per m$^3$

Mr Smith used 43 m$^3$ of water. How much did he pay? Answer: $ ___

1. Calculate the cost for the first 20 m$^3$ of water

$\text{Cost for first } 20\text{ m}^3 = 20 \times 1.50 = \char36{}30$

2. Find the additional volume of water used above 20 m$^3$

$\text{Additional volume} = 43 - 20 = 23\text{ m}^3$

3. Calculate the cost for the additional volume and the total cost

$\text{Cost for additional volume} = 23 \times 2.00 = \char36{}46$
$\text{Total cost} = 30 + 46 = \char36{}76$