Answer:
8
Step-by-step explanation:
The perimeter is the sum of the 3 sides of the triangle.
let the other 2 sides be x and x - 3 , then
12 + x + x - 3 = 31
2x + 9 = 31 ( subtract 9 from both sides )
2x = 22 ( divide both sides by 2 )
x = 11 and x - 3 = 11 - 3 = 8
The 3 sides are 12, 11, 8
with shortest side 8
