Red = 1 unit, purple = 3 units, yellow = 3 units + 41. The three bars total 545 marbles.<br><br>[[model:questions/solutions/q4147.png]]<br><br>• 1 + 3 + 3 = 7 units, plus 41 → 545<br>• 7 units → 545 − 41 = 504<br>• 1 unit → 504 ÷ 7 = 72<br>• Yellow − Red = 2 units + 41 = 144 + 41 = 185<br><br>There are 185 fewer red than yellow marbles.<br>Check: red 72 + purple 216 + yellow 257 = 545. ✓