The cost of three notebooks and four pencils is $7.20. the cost of five notebooks and eight pencils is $13.20. write a system of equations to model this situation. how much does one pencil and one notebook cost?

Notebook cost = $1.2

Pencil cost = $ 0.9

Step-by-step explanation:

Call x at the cost of each notebook and call z at the cost of each pencil.

So we know that 3x added with 4z equals $ 7.20

So:

   (i)

We also know that 5x and 8z = $13.20

Then:

   (ii)

Finally we have a system of 2 equations (i), (ii) and two unknowns x and z.

Then we can solve the system by doing:

-2(i) + (ii)

We have left:

       +

---------------------------------------

Now we substitute the value of x in equation (i) and clear z.

answer: 0

step-by-step explanation: the positive, like 5, + its opposite, like -5 would be 0

5+(-5)=0, or 5-5=0