Maths problem

KuenMa

Can anyone help with the following problem?

At a party, the ratio fo the number of boys to the number of girls was 3:4.   When another 5 boys and 5 girls joined the party, the ratio becamde 7:9.  How many boys were there at the party at first?

Thanks.

Kuen Ma

KuenMa

StrongCat,

Thanks for your suggestion.   I tried this method as well.  However,
the teacher said there are some easier ways to solve the problem.
So I just post it out to ask for help.

Thanks again for your help.

Kuen Ma

KuenMa

Thanks all for your reply.    I have asked my son to check with the teacher.
The teacher showed him some workings on his exercise book but he still could not get it.    When my son asked again, the teacher seemed to be annoyed and asked him to think again.     

The only thing to do maybe to wait for the return of the exercise book and check what the teacher had written down.     I wonder would it be some Olympic Maths method.      Will share with you when the book is returned.
By the way, it is a P6 maths problem.

Kuen Ma