SOLUTION:
Step 1 :
Set up the right triangle with the following:
side a = x
side b = 13 + 3x
side c = 14 + 3x
 
Using pythagorean theorem : 


Step 2 : 
 
Expand this equation by using foil to get:
 

 
Simplifying this equation will give you:
 

Step 3 :
 
Factor this to get:
 
(x-9)(x +3) = 0
 
Solving this will give you x = 9 or x = -3. 
The side length cannot be negative so discard the -3. 
Step 4 :
 
Your side lengths will be:

CONCLUSION:
The side lengths of the triangle are:
9 m , 40 m and 41 m