One side of the rectangle is 12 inches, and the other is 30% of the length of the first. Find the perimeter and area of this rectangle.

It is known from the condition that one side of the rectangle is 12 dm, and the other is 30% of the length of the first. In order to find the perimeter and area of this rectangle, we first need to find the length of the second side.
Let us take the length of one of the sides as 100%, and denote by x dm the length of the second side of the rectangle.
12 dm – 100%;
x dm – 30%;
12 / x = 100/30;
x = (12 * 30) / 100 = 360/100 = 3.6 in length of the second side.
Perimeter of the rectangle:
P = 2 (a + b) = 2 (12 + 3.6) = 2 * 15.6 = 31.2 dm.
Rectangle area:
S = a * b = 12 * 3.6 = 43.2 dm2.