# Response

## (a) GST amount included in the invoice

**$100**

**Working:**
- Invoice total (GST-inclusive): $1,100
- GST is 10% of the GST-exclusive price
- If GST-exclusive price = x, then x + 0.10x = $1,100
- 1.10x = $1,100
- x = $1,100 ÷ 1.10 = $1,000
- GST amount = $1,100 − $1,000 = **$100**

## (b) GST-exclusive price

**$1,000**

**Working:**
- GST-exclusive price = $1,100 ÷ 1.10 = **$1,000**