Calculating Additional Granite Needed for Sam's Aquaponics Garden

Explanation:

Step 1: Convert dkg to grams

1 dkg = 10g

2.3 dkg * 10g = 23g

Sam needs 23 grams of granite in total.

Step 2: Compare total needed with what Sam already has

Sam already has 460g of granite.

23g - 460g = -437g

Since -437g is a negative value, it means that Sam already has more than enough granite for his aquaponics garden. He doesn't need any additional granite.