Tax systems

Hi, F1 q I’m just not getting my head around at all??. F1 exam kit q9. Why net dividend they got as 350,000*75%=262,500 instead of 350,000*70%=245,000 ? It says 30% is tax rate for dividend income for shareholders, and I remember reading somewhere that dividends are paid out of post-tax profits of an entity. The study text? says with imputation system, shareholders get full tax credit so they don’t pay any tax on their dividends, so how’s it possible here there’s imputation system and still shareholders are taxed on dividends ? Sounds like partial imputation system to me…

Also, when we calculate the capital gains tax, is the indexation allowance always just based on cost of original asset + any costs to purchase the asset ? Anything else ? Thanks so much ?.