Lianne charges twice as much to walk a large dog as she does to walk a small dog. This week she has time to walk 10 small dogs and 5 large dogs and she wants to make $100. How much should she charge per small dog? Per large dog?

Let's assume that the cost for walking a small dog is x, and a large dog is 2x.

Set up the following equation and solve:

10x+5 (2x) = 100

10x+10x=100

20x=100

x=5

So for each small dog she walks she should charge $5 and for each large dog she walks she should charge $10.