Problem No. 22. Lines on a plane

Let's draw lines!

Is it possible that 7 lines on a plane have 30 intersection points in total? Can they have twenty intersection points?

Student tip

Find the maximum number of intersection points. Start with two lines, add one at a time, until you reveal the pattern.

Problem No. 17. Cookies

There are 7 different types of cookies in Christine's Bakery that Mary loves. Mary wants to buy 30 cookies. If we suppose that there are enough cookies of each type she loves (at least 30 cookies of each type), in how many different ways can she buy her cookies?

Student tip

Recall how to count all possible ways to select items from a collection, such that the order of selection does not matter.