We need 6.5% to a decimal so..
6.5% /100 = 0.065
$21.30 X 0.065 = 1.3845 tax on the shirt
So.. we add the price of the shirt, and the amount of tax on the shirt
$21.30 + 1.3845 = $22.6845
Answer = $22.68
D. 8 grams
The equation
Ending Amount = Beginning Amount / 2(time / half-life)
32/2^(6/3)
32/2^2
32/4
=8
Rose 8 Fahrenheit
I hope this help you !!!