How to solve exercise in Computer Graphics Using OpenGL Book (Hill)

I dont know how to solve a pretty basic exercise in this book, if you can help me I thank you. Page 152. Exercise 4.2.1 b)
Its an easy one, but I dont know how to solve it and the book doesnt have the answers…

Post the problem for us who don’t have the book, and an answer might come faster.

Its tricky cause it has a figure, but here I go:
4.2.1 Representing vectors as linear combinations. With reference to figure 4.8, what values or range of values for a1 and a2 create the follwing set: The line joining v1 and v2.

The equation is: q = a1v1 + a2v2+(1-a1-a2)v3

v1 = (2,6);v2 = (3,3); v3 = (7,4)

I think you can draw the vectors in a paper and give yourself an idea on how is figure.