Given:
The area of square 1 is 25 square units.
Its length of the side is,
[tex]\begin{gathered} A=s^2 \\ 25=s^2 \\ s=\pm5 \\ s=5\text{ ( since length can not be negative)} \end{gathered}[/tex]
The area of square 2 is 16 square units.
Its length of the side is,
[tex]\begin{gathered} A=s^2 \\ 16=s^2 \\ s=\pm4 \\ s=4\text{ ( since length can not be negative)} \end{gathered}[/tex]
It gives,
Consider the right triangle,
[tex]\begin{gathered} 5^2=4^2+x^2 \\ 25-16=x^2 \\ x^2=9 \\ x=\pm3 \\ x=3\text{ ( since length can not be negative)} \end{gathered}[/tex]
So, the length of square 3 is 3 units. Its perimeter is given as,
[tex]\begin{gathered} P=4x \\ P=4\times3 \\ P=12\text{ units} \end{gathered}[/tex]
Answer: the perimeter of square 3 is 12 units.
