println takes only one variable. In this case u need to convert the
result into a String.
first string is "x["
Second is value of i (if use + with any string it automatically
converts second parameter into string)
third string is "] = "
last value of x[i]

it is not "+i+" it is "x[" + i +"] = " + x[i];
----------------------- string+ var +string+var -> string