Answer: The perimeter of the triangle is 69 cm.
Explanation:
Let us consider the side of the triangle be 3x ,4x and 5x.
According to the question,
The longest side of the triangle be 30 cm.
. 5x=30cm
x=6 cm
So the side of the triangle are 18cm ,24 cm and 30 cm.
The perimeter of the triangle is the sum of sides of the triangle.
so perimeter is =15+24+30=69 cm