Step by step
The question
Question: which is the better buy, A: $4.20 for 6 pens, or B: $6.50 for 10 pens?
A: $4.20 for 6 pens B: $6.50 for 10 pens
The amounts are different, so we can't just look at the prices.
We find the price for 1 pen in each deal.
1 Write both as fractions
We write each deal as a fraction.
The money goes on top.
The pens go on the bottom.
A: $4.206 pens B: $6.5010 pens
2 Divide to get 1 at the bottom
We want 1 pen on the bottom.
In A, we divide the top and the bottom by 6.
In B, we divide them by 10.
$4.20 ÷ 66 pens ÷ 6 $6.50 ÷ 1010 pens ÷ 10
4.2 divided by 6 is 0.7.
6.5 divided by 10 is 0.65.
$0.701 pen $0.651 pen
So A is 70 cents per pen.
B is 65 cents per pen.
$0.70 per pen $0.65 per pen
3 Compare
65 cents is less than 70 cents.
Deal B costs less for each pen.
$0.65 < $0.70
So deal B is the better buy.
Deal B is the better buy
Let's look back.
First: write both as fractions.
Then: divide to get 1 at the bottom.
Last: compare.
Answer
Deal B is the better buy