90% = 90/100 which simplifies to 9/10
C because for every mile the cost increases be $4.75
The answer is C.
Just plug in x = 1 for each of them. The correct one is the one that gives y = 5, which is C.
The quadratic formula is -b + or - the square root of b squared - 4 times the a value and c value over 2a. So the roots would be -1.354249 and -6.645751. I believe these are the roots.