if charlie now has 24 marbles, how many marbles did david give him?

Question

charlie and david collect marbles. the ratio of charlie's marbles to david's marbles is 2:7. david gave charlie some of his marbles and now david has twice as many marbles as charlie. if charlie now has 24 marbles, how many marbles did david give him?

Answer 1

The first thing you have to do is figure out what you know. Here's what you know:

 

• At the beginning, Charlie had 2 marbles to every 7 marbles David had

• David gave Charlie some marbles

• Now David has twice as many marbles as Charlie (David's a nice guy!)

 

Here's the really critical information you know:

 

• Charlie now has 24 marbles.

 

With this information you can figure out the total number of marbles that exist.

 

• The next thing to do is figure out an algebraic equation that will allow us to know exactly how many marbles each boy had at the beginning.

 

• Start by assigning a variable to represent "the marbles" -- it's typical to use x but you could use m or whatever variable you wish.

 

• Now go back to the original information you were given about the ratio of marbles the boys had.

 

• Create an equation given this information and set it equal to the number of marbles you now know the boys have.

 

• You only have to worry about one variable (marbles) so you can easily solve for the marbles/variable and then substitute that back into the original information you have.

 

• Once you know the number of marbles Charlie started out with, subtract that from the 24 marbles we know he has now and you'll have your final answer!

 

I'll check back in a bit if you have additional questions.