The perimeter of the triangle is 120 cm. One of the sides of the triangle is 54 cm, and the other side is three times smaller

The perimeter of the triangle is 120 cm. One of the sides of the triangle is 54 cm, and the other side is three times smaller than the first side. Find the third side.

The perimeter of a triangle (P) is the sum of the lengths of all its sides.
Let the sides of a given triangle: a = 54 cm, b =? and c =?
1) Reduce the first side (a) three times and find out the length of the second side (b):
54: 3 = 18 cm.
2) Find the sum of the two sides of a given triangle:
a + b = 54 + 18 = 72 cm.
3) Then the length of the third side (c) of the triangle will be determined as the difference between its perimeter and the sum of the lengths of the other two sides:
c = P – (a + b) = 120 – 72 = 48 cm.
Answer: The length of the third side is 48 cm.