How do you solve these i’ve tried youtube videos but i can’t figure it out

I'll solve problem 3 (I think it's what you're asking)
All the ones you answered on problem 3 are correct.
I'll solve the rest

c) KM = 26

The diagonals of a rectangle are congruent.
If the measure of one diagonal is 26 (which is 13 + 13), the other one is 26.

d) m∠KLM = 90

It's a rectangle! It's supposed to have 4 corners with right angles.
∠KLM is a corner of the rectangle

f) m∠LJM = 22

Subtract 68 from 90 since you know ∠LJK = 68
90 - 68 = 22

Question 1, 2, and 4 is a bit hard to see.

Have an awesome day! :)