check the picture below.
[tex]\bf A=s^2\qquad s=2\frac{3}{2}\qquad A=\left( 2\frac{3}{2} \right)^2\implies A=\left( \frac{2\cdot 2+3}{2} \right)^2
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A=\left( \frac{7}{2} \right)^2\implies A=\cfrac{7^2}{2^2}\implies A=\cfrac{49}{4}\implies A=12\frac{1}{4}[/tex]