I need help with surface area

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

I’m really confused and need your assist me with this question i’ve never been taught

Alex measured the length of an item to be 3.7 cm. the actual length is 3.5 cm. what is alex’s percent error?