function solve(matrix) {

    let result = 0;

    for (let row = 0; row < matrix.length; row++) {

        for (let col = 0; col < matrix[row].length; col++) {

            if (matrix[row][col] > result) {

                result = matrix[row][col];
            }
        }
    }

    return result;
}

let resultValue = solve([[20, 50, 10],
[8, 33, 145]]);

console.log(resultValue);