What is the multiplicative inverse of 6/7 and -63

Adrawer contains 12 identical white socks, 18 identical black socks and 14 identical brown socks. what is the least number of socks you must choose, without looking, to be certain that you have chosen two socks of the same colour?

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

If the discriminant if a quadratic equation is 4 which statement describes the roots?