ProAnshu

const equations = [
  "7 + x = 20", // x = 13
  "x + 15 = 40", // x = 25
  "12 - x = 5", // x = 7
  "x - 8 = 10", // x = 18
  "-5 + x = 12", // x = 17
  "x + 30 = -10", // x = -40
  "25 - x = -5", // x = 30
  "x - 50 = -100", // x = -50
  "-40 - x = -100", // x = 60

ProAnshu

function sameTest(number) {
  number = number.toString();
  let upSideDown = "";
  let flipText = "";

  for (let i = 0; i < number.length; i++) {
    if (number[i] == "6") {
      upSideDown += "9";
    } else if (number[i] == "9") {
      upSideDown += "6";