Tell whether the two expressions are equivalent 5+3b; 3b+5

Yes they are the same because we can add two numbers in any order. For example, 2+3 = 3+2. This applies with variables as well: 2+x = x+2. All I've done is replace the "3" with "x".

In the case of 5+3b = 3b+5, the 5 and 3b swap places.

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