The perimeter of the rectangle is 50 m, the width of its side is 8 cm. What is the length?

Let’s denote the length of the rectangle as the unknown x. Let’s write the equation according to the condition of the problem, considering that there are 100 centimeters in one meter:
2 * (8 + x) = 5000.
Let’s open the brackets and find the root of the resulting equation:
2 * 8 + 2 * x = 5000,
16 + 8 * x = 5000,
8 * x = 5000 – 16,
8 * x = 4984,
x = 4984/8,
x = 623.
Answer: The length of the given rectangle is 623 centimeters.