(2 + 3) + 5 = 2 + (3 + 5) obey the law of

Number of subsets of a set contains “n” elements is

If 3p = 5q, then what is p : q ?

If 21 cows eat equal to 15 oxen, how many cows will eat equal to 25 oxen?

The length of a rectangle is 2 cms more than its width. If the perimeter is 36 cms., then the area is