What is the definition of a system of linear inequalities?

${a}_{1} {x}_{1} + {a}_{2} {x}_{2} + \ldots + {a}_{n} {x}_{n} \le b$
• ${a}_{1} , {a}_{2} , \ldots , {a}_{n} , b$ are constant.
• the unknown variables are ${x}_{1} , \ldots , {x}_{n}$.