Bill is 1 unit ($4150). His sister has 4 times as much, so 4 units. Altogether that is 5 units.<br><br>[[model:questions/solutions/q3189.png]]<br><br>• Sister = 4 units → 4 × $4150 = $16600<br>• Total = 5 units → $4150 + $16600 = $20750<br><br>Together they have $20750.<br>Check: $4150 + $16600 = $20750. ✓