Flour is 5 units and butter is 1 unit. The difference of 4 units is 30 g.<br><br>[[model:questions/solutions/q4482.png]]<br><br>• Difference in ratio units → 5 − 1 = 4 units<br>• $$\frac{4}{1}$$ units → 30 g<br>• $$\frac{1}{1}$$ unit → 30 ÷ 4 = 7.5 g<br>• Flour → 5 units = 5 × 7.5 = 37.5 g<br>• Rounded to nearest whole number → 38 g<br><br>He used 38 g of flour.<br>Check: Butter = 1 unit = 7.5 g. Flour − Butter = 37.5 − 7.5 = 30 g. ✓