To find CN you have to first make an equation that looks like this
KC+CN=KN
All you have to do for segments is fill in the blank so for this equation it would be
2x+10+4x+1=29
All you have to do is evaluate the equation
You want to combine like terms
6x+11=29
Then you want to subtract 11 from both sides (what you do to one side you must do to the other)
6x=18
Then you divide both sides (follow the same rule as above)
x=3
Now that we know what x equals we can find CN by inputing x into the given equation
4(3)+1
4*3= 12+1=13
CN=13