Converting units of speed

A family used 52 000 litres of water in a month. Water tariffs are \.21 per m$^3$ for the first 40 m$^3$ and \.52 per m$^3$ for the rest. The Water Conservation Tax is 50% of the tariff for the first 40 m$^3$ and 65% of the tariff for the rest. $[1\text{ litre} = 0.001\text{ m}^3]$
What is the total water bill for the month?