A number decreased by 1/3 of itself

The answer is:

X-1/3x

Step-by-step explanation:

Since we do not know what number it is, we would say the number is x. 1/3 of itself is 1/3x so a number minus 1/3 of itself is X-1/3x

56.6

step-by-step explanation:

the ratio of the perimeters is equal to the scale.

the ratio of the areas is equal to the square of the scale.

34 / 20 = k

a / 19.6 = k²

substituting:

a / 19.6 = (34 / 20)²

a = 19.6 (34 / 20)²

a ≈ 56.6