Question

Serena bought 4 packs of pencils and 12 notebooks

for fall semester which cost her $60.00. She then
bought 14 packs of pencils and 7 notebooks for
spring semester which cost her $70.00. How much
did each pack of pencils and each notebook cost?

Answer 1

6

Explanation:

that is what it said the correct answer was

Answer 2

Answer: pencil (x) = 3.00, notebook (y) = 4.00

Explanation:

Let pencils be denoted using 'x', and notebooks 'y'.

4x+12y = 60, 14x+7y=70

Let us use the method of elimination. However, neither variable has the same coefficient, so let us multiply the first equation using 7, and the second using 2.

7(4x+12y = 60) => 28x+84y=420

2(14x+7y=70) => 28x+14y=140

Let us subtract the second equation from the first. This eliminates the first variable x, and gives the equation 70y=280

Dividing either side of the equation by 70, we get y=4.

If we substitute (plug in) y=4 for the first equation we get x=3