It is known that a, B and C are three non negative numbers, and satisfy 3A + 2B + C = 5, 2A + b-3c = 1. Let m = 3A + b-7c, find the maximum and minimum of M Please give me a detailed process

It is known that a, B and C are three non negative numbers, and satisfy 3A + 2B + C = 5, 2A + b-3c = 1. Let m = 3A + b-7c, find the maximum and minimum of M Please give me a detailed process

Because 3A + 2B + C = 5
So 3a