The ratio of pens to pencils is 7:9. If there are 27 pencils, many pens are there?
7/9 = x/27
Cross multiply and solve for x.
or, you can think of it like this
27 = 9*3, so
7:9 = 7*3 : 9*3 = 21:27
To solve this problem, you can set up a proportion using the given ratio to find the number of pens.
The ratio of pens to pencils is 7:9. This means that for every 7 pens, there are 9 pencils.
Let's denote the number of pens as "x". Using the proportion, we can set up the equation:
7 pens / 9 pencils = x pens / 27 pencils
Now, cross-multiply and solve for x:
7 * 27 = 9 * x
189 = 9x
Divide both sides of the equation by 9 to isolate the x:
x = 189 / 9
x = 21
Therefore, there are 21 pens.