Lu-yin predicts that 80% of the people she invites to her party will come. If she wants to have at least 20 guests, how many people should she invite to her party?

25

Step-by-step explanation:

Since she predicts that 80% of the invited people come, she needs to invite a number greater than 20, so that 80% of that number is 20.

Let the number of invited people be x.

80% of x must be 20.

80% * x = 20

0.8x = 20

Divide both sides by 0.8

x = 25

Answer: She should invite 25 people.

Check: Let's find 20% of 25. If it is 20, then 25 is correct.

80% of 25 = 0.8 * 25 = 20

Since 80% of 25 is 20, the answer, 25, is correct.