Suppose I have the below maximization LP problem maximize 2 * x1 - x2 such that x1 + x2 = 0

Suppose I have the below maximization LP problem

maximize 2 * x1 - x2

such that

x1 + x2 <= 10

x1 + 2 * x2 <= 20

where x1, x2 >=0

How can the above maximization problem be converted to the below format?

Prove that any LP optimization problem can be transformed into the following form:

minimize 0 x

subject to Ax = b,

x >= 0