Hi Carol,
When the GST was 7% you bought an item that cost you $1700 including GST. Whoever sold you the item had a price of $x and calculated
1.07 $x = $1700
to get the $1700 which you paid. Dividing both sides by 1.07 gives
$x = $1700 ^{1}/_{1.07}
Thus the selling price was $x and hence the GST was 0.07 of $x. But
0.07 $x = $1700 ^{1}/_{1.07} 0.07 = $1700 0.06542
This is the multiplier you know, ^{1}/_{1.07} 0.07 = 0.0642. Now that the GST is 6% the multiplier is
^{1}/_{1.06} 0.06 = 0.05660
Penny
