3 people get 3 drinks which is written as 3d, add the cost of the pizza and subtract the gift certificate to get the total they spent:
3d + 14.00 - 7.00 = 12.10
Now solve for the cost of a drink:
Simplify the equation:
3d + 7.00 = 12.10
Subtract 7 from both sides
3d = 5.10
Divide both sides by 3:
D = 1.70
The answer is :
C.3d + $14.00 – $7.00 = $12.10; $1.70