Question

Each of A, B and C need a certain unique time to do a certain work. C needs 1 hour less than A to complete the work. Working together, they require 30 minutes to complete 50% of the job. The work also gets completed if A and B start working together and A leaves after 1 hour and B works for a further 3 hours. How much work does C do per hour?

Answer 1

Ax=100%
C(x-1)=100%
A+4B=100%
A+B+C=100%

It's a system composed of four unknowns. Eventually you'll come up with this equation: -3A^2+1000A-30000=0; which will lead you to two possible results: A=33,333 or A=300, if you want B to be positive, you'll use A=33,333, then B will be 16,667 and C=50.