This is probably simple but can someone help me with this??

7.5 units

Step-by-step explanation:

First, create a proportion by picking 2 sides:

2.5/n = 5/15

Next, cross multiply:

5n = 37.5

Finally, divide both sides to isolate the variable:

7.5

Therefore your answer is 7.5 units.

assuming you mean addition: addition and subtraction are reverse operations.

step-by-step explanation:

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