Robbie and his father together are 313 cm. Take out Robbie’s 139 cm to find the father; the gap is the difference.<br><br>[[model:questions/solutions/q2540.png]]<br><br>• Father → 313 − 139 = 174 cm<br>• Difference → 174 − 139 = 35 cm<br><br>The difference in height is 35 cm.<br>Check: 139 + 174 = 313 cm, and 174 − 139 = 35 cm. ✓