The length of the bottom of the rectangular pool is 5 times the width, and the width is 200m less than the length.

The length of the bottom of the rectangular pool is 5 times the width, and the width is 200m less than the length. How much is the pool area?

Let’s introduce the designations for the length and width of the pool bottom:
Let’s assume that the width of the pool bottom is x m. Since the length of the bottom of a rectangular pool is 5 times the width, then it is 5 * x = 5x m.
By the condition of the problem, the width is 200 m less than the length, then we will compose and solve the equation:
5x – 200 = x,
5x – x = 200,
4x = 200,
x = 200: 4,
x = 50.
This means that the width of the pool bottom is 50 m.
Find out what the length of the pool bottom is equal to:
5 * 50 = 250 (m).
Let’s define the area of the pool bottom:
50 * 250 = 12500 (m2).
Answer: the bottom area of the pool is 12,500 m2.