Bead Counter, a bright accounting executive with a large multinational company in Australia, purchased a house in a prestigious riverside suburb on $30$ September $2001$ for $$298,000.$ He used this as his main residence until he was transferred to Head Office overseas on $1$ May of the previous

tax year when the market value of the house was $$430,000.$ It was rented from that day until $31$ May of the current income year when the tenant made him an offer of $$475,000$ which he couldn't refuse.

$($a$)$ Calculate the amount, if any, subject to capital gains tax liability.

$($b$)$ How could Bead minimise any liability?