SOLUTION: Hello my name is Wanda, I have been trying to solve this by using the substitution system. The question is: A class of Math A 30 students contains twice as many girls as boys.

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Question 221560: Hello my name is Wanda, I have been trying to solve this by using the substitution system.
The question is: A class of Math A 30 students contains twice as many girls as boys. Last Friday, when two of the boys were absent and all the girls were there, the number of girls tripled the number of boys. How many boys and how many girls are in the class?
These are the two equations I came up with. But I just can't make it work.
2G = B
3G = B - 2
I'd appreciate your help.
Answer by stanbon(48574) About Me  (Show Source):
You can put this solution on YOUR website!
The question is:
A class of Math A30 students contains twice as many girls as boys. Last Friday,
Equation:
g = 2b
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when two of the boys were absent and all the girls were there, the number of girls tripled the number of boys.
Equation:
g = 3(b-2)

How many boys and how many girls are in the class?
Substitute for "g" and solve for "b":
2b = 3b-6
b = 6 (# of boys before 2 were absent)
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Since g = 3(b-2), g = 3(6-2) = 12 (# of girls)
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Cheers,
Stan H.
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