Answer :
Answer:
David contributes 3 dollar for every 9 dollars that Ken contributes, how dollars will Ken contribute when David contributed 21 dollars.
Step-by-step explanation:
David and Ken are contributing money to buy a textbook.
They agreed, that every 3 dollars that David contributes, Ken should contribute 9 dollars.
Find how much Ken contributed if David when David contribute 21 dollars.
If we set up a proportion equation to solve this problem, we get;
[tex] \frac{3}{9} = \frac{21}{k} [/tex]