(a)[2]
On the day after it is filled, $10$ litres are lost, and this amount rises by $2$ litres each day. How many litres are lost on the $30$th day after filling?
(b)[3]
The tank runs dry during the $n$th day after filling. Determine the value of $n$.
(c)[4]
Suppose instead that $10$ litres of water are lost on the first day and the quantity lost rises by $10\%$ on each following day. Find the percentage of the original $2000$ litres that remains in the tank at the end of the $30$th day after filling.