Question

Ryan earns $5 for each small dog he walks and $8 for each large dog he walks. Today he walked 9 dogs and made a total of $51. How many large dogs did Ryan walk?

Answer 1

Use a system of equations.

(x=# of small dogs, y=# of big dogs)

x+y=9 (times by -5) -5x-5y=-45
5x+8y=51

Then add the equations together and the x's cancel. 

3y=6
y=2

So he walked 2 big dogs and 7 little dogs.