A and B can do work in 10 days. B and C can do it in 12 days. C and can do it in 15 days. If A, B and C work together, they will complete the work in:

40% of a number is added to 120, then the result is double of the number. What is the number ?

The number of marble slabs of 25 cm x 25 cm required to pave the floor of a square room of side 10 meters is:

A student multiplied a number by 4/5  instead of 5/4. The percentage of error is:

Which of the following numbers is divisible by 24 ?