study guide help

[desert canopy]

hey guys, i need some help with my study guide. i dont know what im doing wrong here so i would really appreciate it if someone could explain it to me. the website says that i got it wrong but i dont know how? again please explain to me so i could prepare myself for the test!

[desert canopy]

here is the question:

i dont understand this question either:

i tried using the fractional distance formula but that didnt work for some reason

here’s my work:

i need help finding the right formula for this question too: