9514 1404 393
Answer:
$2.50
Step-by-step explanation:
The question asks for the total cost of a notebook and pen together. We don't need to find their individual costs in order to answer the question.
Sometimes we get bored solving systems of equations in the usual ways. For this question, let's try this.
The first equation has one more notebook than pens. The second equation has 4 more notebooks than pens. If we subtract 4 times the first equation from the second, we should have equal numbers of notebooks and pens.
(8n +4p) -4(3n +2p) = (16.00) -4(6.50)
-4n -4p = -10.00 . . . . . . . . . . . simplify
n + p = -10.00/-4 = 2.50 . . . . divide by the coefficient of (n+p)
The total cost for one notebook and one pen is $2.50.
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<em>Additional comment</em>
The first equation has 1 more notebook than 2 (n+p) combinations, telling us that a notebook costs $6.50 -2(2.50) = $1.50. Then the pen is $2.50 -1.50 = $1.00.
One could solve for the costs of a notebook (n) and a pen (p) individually, then add them together to answer the question. We judge that to be more work.
When you have this type of problem, you need to combine the like-terms and isolate the variable.
3x + 122 = 22x - 11
Add 11 to both sides to get rid of it
3x + 122 + 11 = 22x - 11 + 11 (-11 + 11=0)
3x + 133 = 22x
Then you would bring the 3x to the other side, so subtract 3x from both sides
3x + 133 = 22x
-3x -3x
133 = 22x - 3x
133 = 19x
Then divide both sides by 19 to isolate x
133/19 = 19x/19
133/19 = 7, so x = 7
Hope this helps!!
Answer:
y = 5, -4
Step-by-step explanation:
To solve proportions you cross-multiply.
Now that we have 8 = y^2 - y - 12, we must make the entire trinomial equal to 0 by subtracting 8 from both sides.
y^2 - y - 20 = 0
Factor the trinomial.
(y - 5)(y + 4) = 0
Make both factors equal to 0 to solve for both values of y.
- y - 5 = 0 --> y = 5
- y + 4 = 0 --> y = -4
y = 5, -4
1. y=7/8x +1
2. y=-10x
3. y=2.5x-7
4. y=1.2x
5. y=-5x-8
