The signs of the numbers in the problem matter because if a number is negative in the equation than you're answer could be negative. ex. -3/9= -3 but if the negative sign wasn't there than the answer would be wrong bc the answer would be positive.
hope thats what you need hope it helps.
Answer:
Amount each friend pays for the gift = $20
Step-by-step explanation:
Market price of a gift = $70
The store manager takes $10 off the market price.
Marked down amount = $10
New cost price = Marked price - Marked down amount 
The cost of the gift is divided among three friends.
This means that the cost of gift which is $60 is divided by three to get each one's contribution in the gift.
∴ Amount each friend pays for the gift 
Jake:
Mon- 4 boxes
End of the week- 3x the boxes on Mon
3 x 4 = 12
Sally:
Mon- 2 boxes
End of the week- 4x the boxes on Mon
4 x 2 = 8
12 + 8 = 20 boxes total
For a cone, the equation for volume would be
V = π r^2 h/3.
( volume = pi x radius squared x height / 3)
To find the volume for this question, you would set up the equation like this:
V = π x 2^2 x 12 / 3
Then, following the order of operation, you would do the following:
V = π x 4 x 12 / 3
(You get the 4 from 2 squared)
V = π x 4 x 4
(You get the second 4 from dividing 12 by 3)
V = π x 16
(You get 16 from multiplying 4 and 4)
V = 16π
(You get 16π from multiplying 16 and π, and the number is always in front of the π, so you would never get a π16, it would only be 16π)
So, your volume would be 16π, which is answer D.
I hope I helped! c: