4X-4Y>28
X-Y>7 both side divide by 4
Answer:
This can not be properly answered, because we do not have the length of each trail.
The first step here will be find the length, in miles, for each of the four trails.
As students choose all four trails, the number of miles that each student will bike is equal to the addition of the lenght of the four trails.
Suppose this number is N.
So each student bike N miles, and the company donates $1.75 per mile. Then the amount of money that a single student is N times $1.75, or N*$1.75
The answer to this question is y' = 10x^2 + 6. You have to use the power rule to bring the exponent down as a coefficient and then reduce the exponent by 1. Do it for all the terms using the sum rule for derivatives (derivative of a sum of the sum of its derivatives).
