SOLUTION: franklin school has 3 boys for every 4 girls in the 5th grade. there are 140 students in the 5th grade. how many are boys? How many are girls?

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Question 452838: franklin school has 3 boys for every 4 girls in the 5th grade. there are 140 students in the 5th grade. how many are boys? How many are girls?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The ratio of boys to girls is +3%2F4+
Let b = number of boys
Let g = number of girls
given:
(1) +b+%2B+g+=+140+
(2) +b%2Fg+=+3%2F4+
---------------
(2) +b+=+%283%2F4%29%2Ag+
Substitute this into (1)
(1) +%283%2F4%29%2Ag+%2B+g+=+140+
(1) +3g+%2B+4g+=+560+
(1) +7g+=+560+
(1) +g+=+80+
and
(1) +b+%2B+80+=+140+
(1) +b+=+60+
There are 60 boys and 80 girls