Final answer:
To find out how many grams of dust are left on Eric's desk, subtract the amount of dust he wiped away from the original amount.
Step-by-step explanation:
To find out how many grams of dust are left on Eric's desk, we need to subtract the amount of dust he wiped away from the original amount. If Eric's desk originally had 7/12 grams of dust and he wiped away 5/12 grams, we can subtract 5/12 from 7/12:
7/12 - 5/12 = 2/12 grams
So, there are 2/12 grams of dust left on Eric's desk.