Let 
be the cost, respectively, of a notebook and a pen. If you buy 2 notebooks and 3 pens (which we know is a cost of $14.50), you spend 
Similarly, if you buy 1 notebook and 2 pens (which we know is a cost of $7.50), you spend 
These two equations form the following system:
Multiply the second equation by 2:
Subtract the first equation from the second:
So, a pen costs 0.5 dollars. Plug this equation in the second equation:
Short answer: C
Remark
Since b is all by itself in equation 2, Substitute it into equation 1.
2a + 3b = 5
b = a - 5 Put this result in equation 1. Be sure and use brackets.
2a + 3(a - 5) = 5 Remove the brackets.
2a + 3a - 15 = 5 Notice the -5 inside the brackets becomes - 15
Combine like terms on the left.
5a - 15 = 5 Add 15 to both sides
5a = 5 + 15
5a = 20 Divide by 5
a = 20/5
a = 4
So far, c is the only possible answer.
b = a - 5
b = 4 - 5
b = - 1
Answer:
You will break even on the car wash when you buy 13.5 gallons. As long as you buy that or more, it is cheaper to get the car wash.
Step-by-step explanation:
In order to find this, we need to create equations for both situations. If we let x equal the amount of gallons purchased, we can model the first equation as:
f(x) = 3.35x
And the second equation as:
f(x) = 3.05x + 4.05
Then to find when they equal each other, we can set the two equations equal to each other and solve for x.
3.35x = 3.05x + 4.05
0.30x = 4.05
x = 13.5
This means once you buy 13.5 gallons, the prices will be the same. Any amount over that and the car wash will be cheaper
No! Of course not!!! Balls can be different sizes.......For Example......A football is not round...but the definition of a sphere is a round object.....A football isn't round
