Answer: 7cm , 23 cm and 24.
Explanation:
Given : The three sides of a triangle are n, 3n+2, and 4n−4.
We know that the perimeter of a polygon is the sum of all its sides.
Now, Perimeter of Triangle will be :-

If the perimeter of the triangle is 54 cm , then we have

Add 2 both sides, we get

Divide both sides by 8, we get

Then , 3n+2 = 3(7)+2=23
4n-4 = 4(7)-4=24
Hence, the length of all its side will be 7cm , 23 cm and 24.