1. **Problem statement:** We need to find the number of ways to select 2 biology books from 7 and 2 chemistry books from 6. 2. **Formula used:** The number of ways to choose $k$ items from $n$ items is given by the combination formula: $$\binom{n}{k} = \frac{n!}{k!(n-k)!}$$ 3. **Calculate combinations for biology books:** $$\binom{7}{2} = \frac{7!}{2!(7-2)!} = \frac{7 \times 6}{2 \times 1} = 21$$ 4. **Calculate combinations for chemistry books:** $$\binom{6}{2} = \frac{6!}{2!(6-2)!} = \frac{6 \times 5}{2 \times 1} = 15$$ 5. **Total number of ways:** Since the selections are independent, multiply the two results: $$21 \times 15 = 315$$ **Final answer:** There are 315 ways to select 2 biology books and 2 chemistry books.