math
posted by sherika .
A drum is 2/3 filled with oil.15 litres of oil is removed from the drum. The drum is now 3/5 full, find the capacity of the drum in litres.

OK. So let's create a formula of some sort. So what do we know?
 When we remove 15 L from 2/3 filled drum, we have only 3/5 of the drum full
Let's change this to a mathematical sentence.
Let's say that whole drum holds 'x' Litres
So we can say the following:
2/3 x  15 = 3/5 x
(So 2/3 of the total volume of the drum minus 15 L is equal to 3/5 of the total volume of the drum)
2/3 x  3/5 x = 15
1/15 x = 15
x = 15 * 15
x = 225 L
So the capacity of the drum should be 225 L.