Question

a drum of keroseneoil is 3/4 full..when 15 litres oil is removed from it,7/12 full.find total capacity of drum..

Answer 1

Let, the total capacity of the drum  be x litres.
3/4 of the drum is full that is 3x/4 litres is full.
After  removing 15 litres 7/12=7x/12 litres of the drum is full.
Then, 3x/4-15=7x/12
or, 3x/4-7x/12=15
or, (9x-7x)/12=15
or,2x=15×12
or,x=(15×12)/2
or,x=15×6
or,x=90 litres