Arithmetic Aptitude :: Time and Work
7. A certain sum of money is sufficient to pay either George's wages for 15 days or Mark's wages for 10 days. For how long will it suffice if both George and Mark work together?
Let the money to be paid = 30 rupees.
So, George daily wage = 30/15 = 2
and Mark daily wage = 30/10 = 3.
If both are working,
then 5 rupees to be paid.
So given sum is sufficient for 30 / 5 = 6 days.