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...

[Bob]

Post the problem for us who don't have the book, and an answer might come faster. http://www.opengl.org/discussion_boards/ubb/biggrin.gif

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.