The 1st one
Well it's the same as normal exponents so you multiply 2/3 x 2/3 x 2/3 x 2/3 x 2/3
"At most 12" means "the highest we can go is 12". Think of it as the ceiling. So x can equal 12 or it can be smaller. This means 
<h3>Answer: Choice A</h3>
1. the total of an area under the curve must be equal to one. 2. Every point of the curve must have an vertical height that is 0 or greater.
$21,000-16%
16% of $21,000 is $3,360
$21,000-$3,360=$17,640
1st year would be $17,640
16% of $17,640 is $2,822
$17,640-$2,822 is $14,817
2nd year would be $14,817
16% of $14,817 is $2,370
$14,817-$2,370=$12,446
3rd year would be $12,446
$12,446 rounded would be $12,447
So A) $12,447
Hope this helps out :)
Answer:
add then subtract the anwser