SOLUTION: Using the segment addition postulate to solve for the variable. Suppose M is between L and N. Find the lengths of LM, MN, and LN. LM = 7y + 9 MN = 3y + 4 LN = 143 We saw him wr

Algebra ->  Length-and-distance -> SOLUTION: Using the segment addition postulate to solve for the variable. Suppose M is between L and N. Find the lengths of LM, MN, and LN. LM = 7y + 9 MN = 3y + 4 LN = 143 We saw him wr      Log On


   

Question 152614This question is from textbook Geometry
: Using the segment addition postulate to solve for the variable. Suppose M is between L and N. Find the lengths of LM, MN, and LN.
LM = 7y + 9
MN = 3y + 4
LN = 143
We saw him write up an example and notes but I have no clue what to do. Thank you This question is from textbook Geometry

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
It's always helpful to draw a picture


Photobucket - Video and Image Hosting


Since LN is the entire segment and LM and MN are segments that make up LN, this means that LM+MN=LN (ie the length of LM plus the length of MN equals the length of LN)


So algebraically, this tells us that

%287y+%2B+9%29%2B%283y+%2B+4%29=143


7y%2B9%2B3y%2B4=143 Remove the parenthesis.


10y%2B13=143 Combine like terms on the left side.


10y=143-13 Subtract 13 from both sides.


10y=130 Combine like terms on the right side.


y=%28130%29%2F%2810%29 Divide both sides by 10 to isolate y.


y=13 Reduce.



So the length of LM is

LM = 7(13)+9=91+9=100


and the length of MN is

MN = 3(13) + 4 = 39 + 4 = 43


----------------------------------------------------------------------

Answer:

So LM is 100 units long and MN is 43 units long