Lets set a pen as the variable x and a notebook as the variable y.
3x + 2y = 8.25
2x + 3y = 8
We must solve for one variable and plug it into the other equation.
3x = -2y + 8.25
x = -2y/3 + 2.75
Now we plug x into 2x + 3y = 8
2(-2y/3 + 2.75) + 3y = 8
-4y/3 + 5.5 + 3y = 8
-4y/3 + 9y/3 = 2.5
5y/3 = 2.5
5y = 7.5
y = 1.5
The price of a notebook is $1.50
Now we plug the y value into one of the equations.
2x + 3(1.5) = 8
2x + 4.5 = 8
2x = 3.5
x = 1.75
The price of a pen is $1.75
Now we have to find the cost of two pens and two notebooks.
2(1.5) + 2(1.75)
3 + 3.5
6.5
The cost of two pens and two notebooks would be $6.50
