Question

there are 42 students in a class. 3/4 of boys and 2/3 of girls travel by bus. total no students travel by bus is 30. how many boys are there in the class and gow many girls come to school by bus?

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
number is changed process is same