The value of ds+t÷ds÷dt

If ab = 21 and a+b2a-b2 = 254,then the value of a2+b2+3ab

A man can row upstream at 12 km/hr and downstream at 18 km/hr. The man's rowing speed in still water is

There are 1400 students in a school, 25% of those wear spectacles and 2/7 of those wearing spectacles are boys. How many girls in the school wear spectacles?

A dealer sold an article at 6% loss. Had he sold it for Rs. 64 more, he would have made a profit of 10%. Then the cost of the article is

Rs. 490 is divided among A, B and C such that A's share is half that of B's and thrice that of C's. What is C's share?

A discount series of 15%, 20% and 25% is equal to the single discount of?

The length of the two parallel sides of a trapezium are 16 m and 20 m respectively. If its height is 10 m, its area in square metres is