From the previous working, the sum of the 2 sons' heights is 318 cm.<br><br>&bull; Let younger son = 1 unit, elder son = 1 unit + 12 cm<br>&bull; Total = 2 units + 12 = 318<br>&bull; 2 units = 318 − 12 = 306<br>&bull; 1 unit = 306 ÷ 2 = 153 cm (younger son)<br>&bull; Elder son = 153 + 12 = 165 cm<br><br>Final Answer: 165 cm