The sum of all sides of the rectangle is 20 cm. Its length is 2 cm more than its width. Find the sides of a rectangle.

Let’s mark the sides of the rectangle by “x” and “y”.
Then, it follows from the condition of the problem that (x + x + y + y) = 20 (cm), and y = x + 2 (cm).
We compose a system of equations:
{x + x + y + y = 20, y = x + 2.
Let’s simplify it:
{2x + 2 y = 20, y = x + 2.
We substitute the second equation into the first and solve it:
2x + 2 * (x + 2) = 20;
2x + 2x + 4 = 20;
4x = 20 – 4;
4x = 16;
x = 4 (cm).
We calculate “y”:
y = 4 + 2 = 6 (cm).
Check:
{2 * 4 + 2 * 6 = 20, 6 = 4 + 2 – the equalities are correct.
Answer: The width of the rectangle is 4 cm and the length is 6 cm.