Algebraic Expressions-No. of pens

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lingping7

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The question:
A school bought 300 red and blue pens in separate boxes which cannot contain 2 xoloura. The number of red and blue pens in each box are the same. If each box of blue pens had 70 pens, what could not be the number of red pens.
A 32
B 36
C 45
D 46
Now since the number of boxes is not given to us, I would like to know how to begin this problem, so I can try it on my own.
Thanks in advance
 
lingping7 said:
The question:
A school bought 300 red and blue pens in separate boxes which cannot contain 2 xoloura. The number of red and blue pens in each box are the same. If each box of blue pens had 70 pens, what could not be the number of red pens.
A 32
B 36
C 45
D 46
Now since the number of boxes is not given to us, I would like to know how to begin this problem, so I can try it on my own.
Thanks in advance
Click to expand...

What does that mean?
 
Hello, lingping7!

A school bought 300 red and blue pens in separate boxes which contain one color.
The number of blue pens in each box is the same.
The number of red pens in each box is the same.
If each box of blue pens had 70 pens,
what could not be the number of red pens per box?

. . (A) 32 . . (B) 36 . . (C) 45 . . (D) 46
Click to expand...

Suppose there are 3 boxes of blue pens.
Then there are 210 blue pens and 90 red pens.
The 90 red pens could be packed in 2 boxes of 45 pens each. (C)

Suppose there are 2 boxes of blue pens.
Then there are 140 blue pens and 160 red pens.
The 160 red pens could be packed in 5 boxes of 32 pens each. (A)

Suppose there is 1 box of blue pens.
Then there are 70 blue pens and 230 red pens.
The 230 red pens could be packed in 5 boxes of 46 pens each. (D)

Answer: .(B) 36
 
Thanks. You were a great help, soroban. I was wondering if there was another method to do this, like not take option by option.
 
lingping7 said:
Thanks. You were a great help, soroban. I was wondering if there was another method to do this, like not take option by option.
Click to expand...

Now that you know the answer, see if YOU can find a different way!!!
 
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