The overall length is given as 22.
The line is split into 2 parts X and 3X.
So we have X + 3X = 22
Add X and #X to get 4X:
4X = 22
Divide both sides by 4 to get X:
X = 22 /4
X = 5.5
Now we know what X is so now replace x with 5.5 and solve for LM:
LM = 3X = 3*5.5 = 16.5
