<span>189 + 3 х (x – 99) = 1392 </span><span>180 + 3x – 297 = 1392 </span><span>3x = 1392 – 180 + 207 </span><span>3x = 1689 – 189 </span><span>3x = 1500 </span><span>x = 500</span>