CrossMath

const a = 1;
const b = 2;
const c = 3;
const d = 4;
const e = 5;
const f = 6;
const g = 7;
const h = 8;//hard-coded
const i = 9;

var arr = [a, b, c, d, e, f, g, i];
function shuffleArray(array) {
    for (var i = array.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
}

function check1(x1, x2, x3) {
    return (x1 + x2) * x3 == 20;
}

function check2(x1, /*x2 = 8,*/ x3) {
    return x1 * 8 * x3 == 48;
}

function check3(x1, x2, x3) {
    return (x1 * x2) - x3 == 38;
}

function check4(x1, x2, x3) {
    return x1 + x2 - x3 == 0;
}

function check5(x1, /*x2 = 8,*/ x3) {
    return x1 * 8 * x3 == 80;
}

function check6(x1, x2, x3) {
    return x1 - x2 + x3 == 10;
}

var solved = false;
var attempts = 0;
while(!solved) {
    attempts++;
    shuffleArray(arr);
    console.log(`Running attempt ${attempts}, ${JSON.stringify(arr)}`);

    var x1 = arr[0];
    var x2 = arr[1];
    var x3 = arr[2];
    var x4 = arr[3];
    var x5 = arr[4];
    var x6 = arr[5];
    var x7 = arr[6];
    var x8 = arr[7];

    if (check1(x1, x2, x3) && check2(x4, x5) && check3(x6, x7, x8)
        && check4(x1, x4, x6) && check5(x2, x7) && check6(x3, x5, x8)) {
            console.log(`The solution is: \n${x1}, ${x2}, ${x3}\n${x4}, 8, ${x5}\n${x6}, ${x7}, ${x8}\nThere were ${attempts} checks performed`);
            solved = true;
    }
}