Answer:
80
Step-by-step explanation:
Let notebooks be x and let pencils be y
4x+9y=8.25 (equation 1)
7x+14y=14.00 (equation 2)
Multiply equation 1 by 7
So that you get 28x+63y=57.75
Multiply equation 2 by 4
So that you get 28x+56y=56.00
28x+63y=57.75 -
28x+56y=56.00
-----------------------
7y=1.75
Divide both sides by 7
1.75/7 is 0.25
So, now we know that one pencil costs 0.25 cents
Sub this y value into equation one
4x+9(0.25)=8.25
4x+2.25=8.25
Move 2.25 to the other side as a negative number
4x= 6
Divide both sides by 4
6/4 is $1.50
So, one pencil is equal to 0.25 cents and one notebook is equal to $1.50
Slope intercept form is y = mx + b
y = -2x + 4
