It is associative property
$3.18 when the tax is applied to each bottle separately or at the end of the bill.
Answer: 1,000
First, you have to find how much 7.5% is coming out of 10,000. So in this case it's 750. Multiply 750 by 12 years. Thats 9000, you then subtract 9000 and 10,000 to get 1,000.
3f + 2g = 30 . . .(1)
f + 2g = 26 . . . .(2)
(1) - (2) => 2f = 4 => f = 4/2 = 2
From (2), 2 + 2g = 26 => 2g = 26 - 2 = 24 => g = 24/2 = 12
Therefore, f = 2 and g = 12