interpret(1, ["+"], [1]) → 2

interpret(4, ["-"], [2]) → 2

interpret(1, ["+", "*"], [1, 3]) → 6

interpret(5, ["+", "*", "-"], [4, 1, 3]) → 6

function interpret(num, arr2, arr3) {
    for(var i = 0; i < arr2.length; i++){
        if(arr2[i]== "+" && arr2.length === 1) return num + Number(arr3[i]);
        if(arr2[i]== "-" && arr2.length === 1) return num - Number(arr3[i]);
        if(arr2[i]== "*" && arr2.length === 1) return num * Number(arr3[i]);
    }
}