Boy-girl ratios

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Boy-girl ratios

by lilu » Wed Mar 04, 2009 10:50 am
I hope I'm not duplicating this question.

The ratio of boys to girls in Class A is 3 to 4. The ratio of boys to girls in Class B is 4 to 5. If the two classes were combined, the ratio of boys to girls in the combined class would be 17 to 22. If the number of boys in Class B is one less than the number of boys in Class A, and if the number of girls in Class B is two less than the number of girls in Class A, how many girls are in Class A?


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Re: Boy-girl ratios

by kamu » Wed Mar 04, 2009 11:00 am
lilu wrote:I hope I'm not duplicating this question.

The ratio of boys to girls in Class A is 3 to 4. The ratio of boys to girls in Class B is 4 to 5. If the two classes were combined, the ratio of boys to girls in the combined class would be 17 to 22. If the number of boys in Class B is one less than the number of boys in Class A, and if the number of girls in Class B is two less than the number of girls in Class A, how many girls are in Class A?


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use the bold part .

3x=4y+1
4x=5y+2

x=2
y=3

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Re: Boy-girl ratios

by El Cucu » Wed Mar 04, 2009 11:49 am
kamu wrote:
lilu wrote:I hope I'm not duplicating this question.

The ratio of boys to girls in Class A is 3 to 4. The ratio of boys to girls in Class B is 4 to 5. If the two classes were combined, the ratio of boys to girls in the combined class would be 17 to 22. If the number of boys in Class B is one less than the number of boys in Class A, and if the number of girls in Class B is two less than the number of girls in Class A, how many girls are in Class A?


8
9
10
11
12
12.


use the bold part .

3x=4y+1
4x=5y+2

x=2
y=3
x=3 y=2
12 girls