The strings cost $14. you would take the total cost ($72) and subtract the cost of the book ($16) and you would get $56. you would then divide 56 by the number of book bought (4 in all) and you would get $14.
The "unit rate" appears to be $20 per ticket.
The height of the platform would be the last part of the equation
45 feet
Answer:
The answer should be -2x^2+6x
First, you want to get x by itself on one side. We write the equation as

. Since 14 is being subtracted from

, we add it to both sides to cancel it out,

or

.
Your answer would be D.