161?85?65?89 = 100, then use + or - in place of ? and take + as m,- as n then find value of m-n.?

In a cycle race there are 5 persons named as J,K,L,M,N participated for 5 positions so that in how many number of ways can M finishes always before N?

Rahul took a part in cycling game where 1/5 ahead of him and 5/6 behind him excluding him. Then total number of participants are

If a refrigerator contains 12 cans such that 7 blue cans and 5 red cans. In how many ways can we remove 8 cans so that atleast 1 blue can and 1 red can remains in the refrigerator.

There are 16 people, they divide into four groups, now from those four groups select a team of three members,such that no two members in the team should belong to same group.

How many five digit numbers are there such that two left most digits are even and remaining are odd and digit 4 should not be repeated.

7 people have to be selected from 12 men and 3 women, Such that no two women can come together. In how many ways we can select them?

Tennis players take part in a tournament. Every player plays twice with each of his opponents. How many games are to be played?

Find the unit digit of product of the prime number up to 50 .

If [$x^{1/3}$] - [$x^{1/9}$] = 60 then find the value of x.