If a3 + b3 = 28 and a + b = 4, then what is the value of ab?

If 2x/3 - [5(4x/5 - 4/3)]/2 = 1/3, then what is the value of x?

The simple and compound interest that can be earned in two years at the same rate is Rs 4000 and Rs 4180 respectively. What is the rate (percent per annum) of interest?

Excluding stoppages, the speed of a train is 120 kmph and including stoppages, it is 50 kmph. For how many minutes does the train stop per hour?

50% of a = b, then b% of 40 is the same as _________ of a.

A trader had 630 kgs of rice. He sold a part of it at 15% profit and the rest at 8% profit, so that he made a total profit of 12%. How much rice (in kgs) did he sell at 8% profit?

What is the average of all numbers between 9 and 90 which are divisible by 8?

What is the fourth proportional to 336, 288 and 161?