Answer:
x = 10
Step-by-step explanation:

Step 1 : Collect like terms and simplify

Step 2 : Divide both sides of the equation by 2

Step 3 : Simplify by cross cancellation of common term : 2

L = 2W
P = 2L + 2W
Plug 2W in for L.
54 = 2(2W) + 2W
54 = 4W + 2W
54 = 6W
Divide both sides by 6
W = 9
L = 2* 9
L = 18
A = L * W
A = 9 * 18
A = 162 units^2
Amy's current age is 16 years greater than Peter's age, so Amy's current age is equal to x + 16.
6 years ago, Amy's age was equal to twice that of Peter's age at that point, so her age was 2(x - 6).
As currently her age is x + 16 then 6 years ago her age was x + 16 - 6, which is x + 10.
As 6 years ago her age was equal to 2(x - 6) and x + 10, we can see that x + 10 = 2(x - 6).