Me on number 10 i have the answer but explain why

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

y=mx+b

step-by-step explanation:

m is slope, b is y-intercept