



 
Hi Andy, Think about what you would do if you knew the price before the hst and you wanted to add the 13%. If the price before the hst were $\$P$ then you would find the cost $\$C$ after the hst by \[1.13 \times \$P = \$C\] If you divide both sides of this expression by $1.13$ you get \[\$P = \frac{\$C}{1.13}\] This is the formula you need. Divide the cost which includes the hst by 1.13 to find the price before the hst. I hope this helps,  


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