Math CentralQuandaries & Queries


Question from Sharon, a teacher:

The question was asked before but it was based on a G.S.T of 7% and I am now interested in the answer for 5% G.S.T.
It usually comes up when I husband bring homes a gas bill that doesn't break down the gst and pst, but rather just gives him the total cost I have to know how much GST he paid. If it is Diesel the PST isn't included but if it is regular gas he pays both. PST is 7%.


As I showed in my response to Donna, if you pay the 5% GST and the 7% PST and the total you pay is $T then the amount $A before tax is

$A = $T/1.12

For Diesel where the tax is only the 5% GST

$A = $T/1.05


About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS