900÷(5-2)=900÷3=300 (Ben)

300×5= 1500 (Ben)

300×2=600 (Ben)

A: Storybook 1500, Science and Technology Book 600.

900 ÷ (5-2) × (5+2) = 900 ÷ 3× 7 = 2100 (Ben)

A: There are 265,438+000 story books and science books.

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