Mrs Lim bought a watch at a discount of 15% and she paid $124.10, not including GST. What is the original price of the watch including 8% GST? Answer: $ ___

1. Find the original price of the watch before the discount and before GST.

Let the original price be $100\%$.
Since the discount is $15\%$, the price paid is $100\% - 15\% = 85\%$.
$85\% \rightarrow \char36{}124.10$
$1\% \rightarrow \char36{}124.10 \div 85 = \char36{}1.46$
$100\% \rightarrow \char36{}1.46 \times 100 = \char36{}146.00$

2. Calculate the original price including 8% GST.

Original price including $8\%$ GST $= \char36{}146.00 \times (100\% + 8\%)$
$= \char36{}146.00 \times 1.08$
$= \char36{}157.68$