In triangle ABC, side AB is 27 cm and it is 3 times larger than side BC

In triangle ABC, side AB is 27 cm and it is 3 times larger than side BC Find the length of side AC if the perimeter of triangle ABC is 61 cm.

Condition:
AB = 27 cm;
AB = 3 * BC;
P triangle ABC = 61 cm;
AC =?
The perimeter is the sum of the lengths of the sides of the triangle.
The problem is solved in 3 steps.
1) 27: 3 = 9 cm BC side length.
2) 27 + 9 = 36 cm the sum of the lengths of the two sides AB and BC.
3) 61 – 36 = 25 cm speaker side length.
Answer: 25 cm.