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.