SOLUTION: Hi there were 121 pupils in a class. 8/9 of the boys and 4/5 of the girls were greek.the rest were english.if there were 104 greek pupils, how many greek boys were in the class.

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Question 1103366: Hi
there were 121 pupils in a class. 8/9 of the boys and 4/5 of the girls were greek.the rest were english.if there were 104 greek pupils, how many greek boys were in the class.
thanks
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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There were 121 pupils in a class. 8/9 of the boys and 4/5 of the girls were Greek.
The rest were English.
If there were 104 Greek pupils, how many Greek boys were in the class.
:
Find the total no. of boys
:
let b = no. of boys
let g = no. of girls
then
b + g = 121
g = 121 - b
and
8%2F9b + 4%2F5g = 104
get rid of those annoying fractions, multiply eq by 45, cancel and you have
5(8b) + 9(4g) = 4680
40b + 36g = 4680
Replace g with (121-b)
40b + 36(121-b) = 4680
40b + 4356 - 36b = 4680
40b - 36b = 4680 - 4356
4b = 324
b = 324/4
b = 81 boys
Find the no. of Greek boys
8%2F9*81 = 72 Greek boys