# Working backwards

• Apr 15th 2008, 05:40 PM
kazzerbee
Working backwards
if the total of a bill including GST came to 56.70 and GST is 6% what was the amount of the bill before GST was added? please show how u got this, thanks.
• Apr 15th 2008, 06:21 PM
TheEmptySet
Quote:

Originally Posted by kazzerbee
if the total of a bill including GST came to 56.70 and GST is 6% what was the amount of the bill before GST was added? please show how u got this, thanks.

Let x be the pretax amount then

$x+.06x=56.70 \iff 1.06x=56.70 \iff x=\frac{56.70}{1.06}=53.49$