Formula used: Area of an equilateral triangle = \(\frac{sqrt(3)}{4}*side^2\)

Let the side of the triangle be 1

The side of the new triangle reduces by 20%(becomes \(0.8 = \frac{4}{5}\))

If the area of the first triangle is \(\frac{sqrt(3)}{4}*1^2\),

the are of the second triangle is \(\frac{sqrt(3)}{4}*\frac{16}{25}\)

Therefore the ratio of the two triangles is \(\frac{25}{16}\)

The difference is \(25-16 = 9\) and the resulting percentage is \(\frac{9}{25}*100 = 36%\)(Option A)

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