To calculate the selling price of an item which includes GST of 10%, you use the formula SP=1.1 x CP , where CP is the cost price without GST. (A) rearrange this formula to make CP the subject.

(B) use your formula from (a) to find the cost price of an item without GST If the selling price is $65.45

(C) hence, calculate the amount of GST on an item whose selling price is $65.45