You are Here: Home >< Maths

# Word problem Watch

1. The number of Roberto's baseball cards is the number of David's cards. If Roberto gives of his cards to David, what will be the ratio of Roberto's cards to David's cards?

I have tried the get the solution but just don't seem to come up with a solvable equation:

Let r represent the number of card's that Roberto has.
Let d represent the number of card's David has.

Obviously this makes no sense. Where am I going wrong?

Any help much appreciated!
2. (Original post by supreme)
The number of Roberto's baseball cards is the number of David's cards. If Roberto gives of his cards to David, what will be the ratio of Roberto's cards to David's cards?

I have tried the get the solution but just don't seem to come up with a solvable equation:

Let r represent the number of card's that Roberto has.
Let d represent the number of card's David has.

Obviously this makes no sense. Where am I going wrong?

Any help much appreciated!
I'm not sure that equation is entirely correct. But look at it this way:

So we have r:d ratio

= (3d)/4 : d

This is the beginning ratio, with Roberto on the left

Now, roberto gives half to david, what would the new ratio be?

x:y?
3. (Original post by 2710)
I'm not sure that equation is entirely correct. But look at it this way:

So we have r:d ratio

= (3d)/4 : d

This is the beginning ratio, with Roberto on the left

Now, roberto gives half to david, what would the new ratio be?

x:y?
Thanks but I don't get how this helps because what am I meant to do with:

r/d = (3d/4 - 3d/8)/(d + 3d/8)?
4. (Original post by supreme)
Thanks but I don't get how this helps because what am I meant to do with:

r/d = (3d/4 - 3d/8)/(d + 3d/8)?
Lol, thats you answer! Just simplify it tho.
5. (Original post by supreme)

[latex]
\dfrac {r}{2} = \dfrac {3d}{4} + \dfrac {r}{2}
latex]
This is the error as you have said they have the same cards after the exchange

Try with numbers

Let David have 40 and Roberto have 30
Roberto gives 15 to David

R : D = 15 : 55 = 3 : 11

So now try with letters

Let David have d and Roberto have 3/4 d
Roberto gives 3/8 d to David

R : D = 3/4 d - 3/8 d : d + 3/8 d = 3d/8 : 11d/8 = 3 : 11

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 16, 2013
Today on TSR

### Last-minute PS help

100s of personal statements examples here

### Loneliness at uni

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.