Question

there are 42 students In a class out of this 3 upon 4 of the boys and 2 upon 3 of the girls come to school by bus the total number of boys and girls of the same class who come to school by bus is 30 how many boys are there in class

Answer 1

B+G=42
B=42-G
3B/4+2G/3=30
3(42-G)/4+2G/3=30
(126-3G)/4+2G/3=30
[3(126-3G)+4(2G)]/3*4=30
[378-9G+8G]/12=30
-G+378=360
-G=360-378
-G=-18
G=18 THE NUMBER OF GIRLS IN THE CLASS.
B+18=42
B=42-18
B=24 THE NUMBER OF BOYS IN THE CLASS.
PROOF:
3/4*24+2/3*18=30
18+12=30
30=30