# Blog

## Trolls, kings, and solving systems of equations

2012-10-31 18:37:00 GMT

Sal has created new algebra videos to explain solving systems of equations:

**Trolls, Tolls, and Systems of Equations**

Then check out the follow-up videos on Solving the Troll Riddle Visually and Solving Systems Graphically.

**Elimination**

The King’s planning a party and needs your help figuring out how many cupcakes to order.

**King’s Cupcakes: Solving Systems by Elimination**

This video leads into the first exercise on elimination, which has a new guide video: Simple Elimination Practice.

Then, the King needs more party planning help in managing The Potato Chip Issue:

**How many bags of potato chips do people eat?**

This leads into the next exercise on elimination, which also has a new companion video.

**Substitution**

Next, a little bird visits the King to teach him a new solving method: substitution.

**Talking bird solves systems with substitution**

The exercise using substitution has a new companion video.

**Solutions to Systems**

Sal then investigates special situations you may run into, including systems without a solution:

**Inconsistent systems of equations**

and systems with infinite solutions:

Our exercise on how many solutions a system of equations has also comes with a new companion video.