7/9 = x/27
Cross multiply and solve for x.
The ratio of pens to pencils is 7:9. If there are 27 pencils, many pens are there?
2 answers
or, you can think of it like this
27 = 9*3, so
7:9 = 7*3 : 9*3 = 21:27
27 = 9*3, so
7:9 = 7*3 : 9*3 = 21:27