The two sides of the triangle have the same length equal to 60 dm, the perimeter

The two sides of the triangle have the same length equal to 60 dm, the perimeter of the triangle is 1600 cm, find the length of the third side.

Let us determine the total length of the two known sides of the triangle, knowing by the condition of the problem that the length of one side is 60 decimeters:
60 + 60 = 120.
For a correct calculation, we will bring the found value to a single unit of measurement – centimeters, knowing that, by definition, there are 10 centimeters in 1 decimeter:
120 * 10 = 1200.
Determine the length of the third side of the triangle, knowing that the perimeter of the triangle is 1600 centimeters:
1600 – 1200 = 400.
Answer: The length of the third side is 400 centimeters.