Which is the better buy: 3 shirts for $15 or 5 shirts for $20?

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Jorge planted flowers in his garden he planted one row of 12 tulips and one row of 36 daisies george's friend kylie has a garden with 75 flowers in it kylie's garden only contains tulips and daisies. is it possible for kylie‘s garden she have the same ratio of tulips to daisies as george's garden?

How many ordered pairs of positive integers satisfy xy=32?