What can name part of a whole or a group

Which expressions are equivalent to k/2 choose 2 answers: a k-2 b 2/k c 1/2k d k/2 e k+k

The area of square garden is 300m squared. how long is the diagonal?

Your food costs are $5,500. your total food sales are $11,000. what percent of your food sales do the food costs represent?