Arnie plans to eat 4 twinkies during his lunch break. so far he has eaten 3. what percent of his goal has been achieved?

0.75%

If Arnie intends to eat 4 twinkies during his lunch break, and he has already eaten 3, then he has already achieved 75% of his goal.

This can be wrote as a fraction: 3/4. Since the 3 represents how many he has already eaten and the 4 represents the total amount (that he intends, anyway), you can divide these. When you divide them, you get 0.75, or 75%.