First take the 19 teachers out of 406 to get the students. Cut the students into 9 units: 4 are boys, the other 5 are girls.<br><br>[[model:questions/solutions/q5279.png]]<br><br>• Students → 406 − 19 = 387<br>• 9 units → 387<br>• 1 unit → 387 ÷ 9 = 43<br>• Girls − boys → 5 units − 4 units = 1 unit = 43<br><br>There are 43 more girls than boys.<br>Check: boys 172 + girls 215 = 387; 215 − 172 = 43. ✓