Use the top-level ratio 4:1 to find how many cars and motorcycles there are, then break each group down using sub-ratios.
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• Top-level ratio 4:1 means 5 units in total.
• 50 ÷ 5 = 10 per unit.
• Cars: 4 × 10 = 40
• Motorcycles: 1 × 10 = 10
For the cars (sub-ratio 3 + 1):
• 4 parts = 10 per part
• red: 3 × 10 = 30
• blue: 1 × 10 = 10
For the motorcycles (sub-ratio 1 + 1):
• 2 parts = 5 per part
• red: 1 × 5 = 5
• blue: 1 × 5 = 5
Total red: 30 + 5 = 35.
Check: 40 + 10 = 50 = total (50). ✓
Final Answer: 35