book Maths Puzzle Numerical Ability

Wjy do we use liters instead of using units square?

Read Solution (Total 0)

book Other Question

It takes you 6 hours to do a job. It takes a friend 3 hours to do the same job. How long would it take both of you working together to do the job? x/2 + y/4 = 1/7
x/4 + y/6 = 1/4

solve for x and y
I got x = 29/49 if this is correct please help me determine y.
thank you.