In the town of Muckaluck, m litres of water are required per household per month. At this rate, if there are n households in Muckaluck, how long (in months) will p litres of water last?
A. p /mn
B. npm
C. mn / p
D. np / m
E. mp / n
Choose sensible numbers to work the problem out. Then go back to letters.
So if 100 liters are needed per month, 20 households will need 100 x 20 liters per month.
1000 liters will last 1000/ 100 x 20 months. Putting the letters back = p/mn