Clara estimates that the length of a hiking trail is 5.75 km. she later learns that its actual length is 6.25 km.

what is the percent error in clara's estimate, to the nearest tenth of a percent?

Here are the necessary steps for completing this.

1. take the estimated number and subtract it from the actual number EXAMPLE:     5.75-6.25 = -0.5

2. then take the answer and multiply it by 100% 
EXAMPLE:     -0.5*100 = -50

3. next take the multiplied answer and divide it by the actual number
EXAMPLE:     -50÷6.25 = -8

4. finally take the answer and absolute value it then put the number as a percent
EXAMPLE:      -8=8       8=8%

your answer is 8%

the answer for this is 0.25 km. : )