You estimate that a kitten weighs 15 pounds. the actual weight of the kitten is 8 pounds. find the percent error

This is simple. You thought the kitten weighed 15 pounds but really weighs 8. The first thing you would do is subtract the guess minus the actual. 15 - 8 = 7. That person was off by 7. So you would put it as a fraction over the actual weight. 7/8. Then turn your fraction into a decimal and turn that decimal into a percent. 7 divided by 8 = 0.875. 0.875 as a percent is 87.5%. So the percent error is 87.5%. Hope I helped. :)