I understand the idea of Best Worst Method for multi criteria decision making

and i know that there is a solver to get the weights but i need to understand the mathematical equation and know how to solve it with my own self.

Can any one help me?

{|𝑤𝐵 − 𝑎𝐵𝑗𝑤𝑗|} ≤ 𝜉L for all j

{|𝑤𝑗 − 𝑎𝑗𝑊𝑤𝑊|} ≤ 𝜉𝐿 for all j

Σ𝑤𝑗 = 1, 𝑤𝑗 ≥ 0 for all j