A package

of pens contains one red pen and four black pens. If 20 black pens are purchased, how many red pens are purchased.

If each pack contains 4 black pens, then 20/4 packages were purchased. Take it from there.

I think thats not all corccet

To find out how many red pens are purchased when 20 black pens are bought, let's calculate it step by step:

1. Start with the given information: the package contains one red pen and four black pens. So, the ratio of red pens to black pens in the package is 1:4.

2. Determine the number of red pens in the package: Since the ratio is 1:4, we can divide the number of black pens by four to find the number of red pens. Thus, 4 black pens ÷ 4 = 1 red pen.

3. Find out the number of red pens when 20 black pens are purchased: If we purchase 20 black pens, the ratio remains the same. Therefore, for every 4 black pens, we have 1 red pen. Thus, the number of red pens purchased would be 20 black pens ÷ 4 = 5 red pens.

Therefore, when 20 black pens are purchased, 5 red pens are also purchased.