Which output in this table is incorrect

Answer:
B
Step-by-step explanation:
This is quite a trial and error question.
Given from the table
$1 cost of item = $0.08 tax on item
$2 cost of item = ($0.08x2) tax on item = $0.16 tax on item
$3 cost of item = ($0.08x3) tax on item = $0.24 tax on item
$8.50 cost of item = ($0.08x8.50) tax on item = $0.68 tax on item
$10 cost of item = ($0.08x10) tax on item = $0.80 tax on item
The only one that is different is the incorrect value therefore $0.64 is the incorrect one.