A scientist planted 120 seeds, and 90 sprouted. What percent of the seeds failed to sprout?

Do 120 seeds - 90 that have sprouted.

120-90 = 30

30 divide by the total number of planted 120 seeds

30/120 = 1/4

1/4 times 100 to get the percent

1/4*100

Cross out 4 and 100, divide by 4. 4/4 = 1

100/4 = 25

1/4=25 %

Answer: 25%