Solve the proportion
posted by seb .
A recipe for cookies calls for 4 eggs. The recipe makes 6 dozen cookies. how many eggs would be need to make 21 dozen cookies?

4 / 6 : x / 21
Cross multiply.
We'll be glad to check your answer. 
63 eggs?

No, from the proportion, you should see that x will be less than 21, not more.
4/6 : x/21 crossmultiplied ~~> 4*21=6x
Now solve for x. Multiply 4*21 and then divide both sides by 6. What's the answer? 
14 eggs!

Right! :)