Question

A pen costs twice as much as a pencil. The total cost of 1 1 pen and 1 1 pencil is $2.10 $2.10 . If p p represents the cost of 1 1 pencil, which equation could you use to find p p ?

Answer 1

Answer:

Step-by-step explanation:

You didn't list any choices here, but it doesn't matter. There's only one way to get to the answer so we'll work it through and you can match it up to your choices. The only thing I don't know is how pens is identified if pencils is "p". So I'm going to use the words "pens" and "pencils" and you can take it from there at the end.

If a pen's cost IS twice as much as a pencil...

the word "is" indicates an equals sign, the words "twice as much" indicates 2 multiplied by something. To put that above sentence into an algebraic expression:

pen = 2 pencils

Now for the money part of this.

The total cost of 11 pens and 11 pencils IS (there's that word again!) 2.10

Therefore,

11 pens + 11 pencils = 2.10

But we know from the first expression that pen = 2 pencils so we make the substitution:

11(2 pencils) + 11 pencils = 2.10

I'm not sure how far you are to go with this. That's the main equation you need to solve this. If you were to go further with it you would distribute the 11 into the set of parenthesis to get:

22 pencils + 11 pencils = 2.10 and combine like terms:

33 pencils = 2.10 so

1 pencil is approximately $.06