Use the top-level ratio 2:5 to find how many dolls and robots there are, then break each group down using sub-ratios.
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• Top-level ratio 2:5 means 7 units in total.
• 70 ÷ 7 = 10 per unit.
• Dolls: 2 × 10 = 20
• Robots: 5 × 10 = 50
For the dolls (sub-ratio 1 + 3):
• 4 parts = 5 per part
• large: 1 × 5 = 5
• small: 3 × 5 = 15
For the robots (sub-ratio 2 + 3):
• 5 parts = 10 per part
• large: 2 × 10 = 20
• small: 3 × 10 = 30
Total small: 15 + 30 = 45.
Check: 20 + 50 = 70 = total (70). ✓
Final Answer: 45