Gardens

I have a garden in the shape of a square with a side length of 0.02 kilometers. The neighbor has a large garden, and we share one side of the garden. I bought from a neighbor's garden that the area of my garden increased to 5 ares.
a/ By how many acres I purchased from the neighbor?
b / how many meters will I move my fence towards a neighbor's garden if I buy it?

Correct answer:

a =  1 a
b =  5 m

Step-by-step explanation:

$$\begin{gathered} x=0.02\cdot 1000=20 \\ S=x^2=20^2=400 \\ a=5-S/10^2=5-400/10^2=1\text{a} \end{gathered}$$

$b=a\cdot 10^2/x=1\cdot 10^2/20=5\text{m}$

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