The ratio of the number of boys to girls at a party is 3 : 4. Six boys leave the party. The ratio of the number of boys to girls at the party is now 5 : 8. How many girls are at the party?

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Answer 1 · 2016-07-08T06:55:14

The boys are 36, the girls 48

Let b the number of boys and g the number of girl, then

#b/g=3/4#

and

#(b-6)/g=5/8#

So you can solve the system:

#b=3/4g and g=8(b-6)/5#

Let substitute in b in the second equation its value #3/4g#

and you will have:

#g=8(3/4g-6)/5#

#5g=6g-48#

#g=48#

and #b=3/4*48=36#