A subtraction problem can be turned in to an addition problem because of negative numbers. Take 5-2=3 for example. If you change 5-2 into an addition problem then you would but he addition sign and a negative sign on 2. This will then leave you with the problem looking like 5+ -2. If you add 5 and -2 you will still get three.
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 
Answer:
D
Step-by-step explanation: