Final answer:
To find the percent decrease, subtract the final value from the initial value, divide the difference by the initial value and multiply by 100%.
Step-by-step explanation:
To find the percent decrease, we need to calculate the difference between the starting value and the final value, and then divide that difference by the starting value. In this case, the starting value is 64 dozen donuts and the final value is 21 dozen donuts. The difference is 64 - 21 = 43 dozen donuts. Now, we divide the difference by the starting value: (43 / 64) * 100% = 67.19%. Therefore, the percent decrease is 67.19%.