Logan H. answered • 07/06/20
Math Wizard for Pure and Applied Math
Hello Oyin!
I hope I can help you today.
First, let's analyze the problem. We know that we were able to buy 5 pens for $3.25, and we want to know how much it would cost for 2 pens.
When you go grocery shopping and want to buy a candy bar, the candy bar has a price right?
For example, $1 per Twix bar.
Let's say you bought 5 Twix bars.
That would be.. $1 + $1 + $1 + $1 + $1 = $5.
So, in other words, the price of the item times the number of it you bought.
One dollar times five purchases = 5 dollars.
So, if I told you that you bought 5 twixes for a total of $5 dollars, how would you figure out how much each Twix cost?
Well, since each Twix costs the same amount, you should be able to take the total cost and split it into 5 equal-sized chunks.
So we can use division to accomplish this:
5 $ total / 5 twixes purchased = $1 dollar per each Twix.
Likewise, in the problem you have above, we spent $3.25 on 5 pens.
If we can split the $3.25 into 5 equal piles of money then we can figure out how much each pen cost us.
We can use division to split the number into 5 equal piles.
$3.25 / 5 =
0.65
5 |3.25
-30
25
-25
00
You can use long division or a calculator to do this division.
As you can see, we find out that:
$3.25 / 5 = 0.65.
So we have 5 equal sized piles of 65 cents.
So each pen costs 65 cents (0.65 )
But we want to know how much it costs for 2 pens right?
So we can just "buy" a pen twice.
If each pen costs 0.65, we get:
0.65 (one purchase) + 0.65 (second purchase) = 2 * 0.65 = $1.30
Since multiplication is just repeated addition, we can just multiply the price times the number of items we want.
2 * 0.65 tells us how much it costs for 2 pens.
3 * 0.65 tells us how much it costs for 3 pens.
Just like how 5 * 0.65 tells us how much it costs for 5 pens.
So the answer is that it costs $1.30 for 2 pens.
I hope this helps! Let me know if you have any questions!
