Write the next sentence in the following story.

How to solve matrices
Verify that you have sufficient data.
In order to get a unique solution for each variable in a linear system using a matrix, you need to have as many equations as the number of variables that you are trying to solve. For example, with variables x, y and z, you would need three equations.

Available choices:
1). In the equation x, y + y = y, this equals 80. When you like a number in linear equations, multiply that number by the number of variables to get 100.
2). If you have four variables, you need four equations. If you have fewer equations than the number of variables, you will be able to learn some limiting information about the variables (such as x = 3y and y = 2z), but you cannot get a precise solution.
3). Pick a zero-point solution for both variables. The simplest solution to solving this problem is to consider your data.
4). Make sure that you understand the solutions of all variables. This can help you to make incremental benchmarks about which variables to break down.. The answer should be
2).