The town library is having a used book sale. The Graph below can be used to find the cost y to buy x books. The total cost includes the admission fee. What is the equation of the line shown?
A: y = x + 4
B: y = x - 4
C: y = -x + 4
D: y = -x - 4
Answer: The answer is A because, y = x + 4. If you put the two numbers into that equation you will get : 5 = 1 + 4, which is true. For the other one, 7= 3+4, is also true. If you try the other ones, the equation will be false.
