Description for Correct answer:
\( \Large a_{1} \)=\( \Large \frac{68}{4} \)=17cm

and \( \Large a_{2} \)=\( \Large \frac{60}{4} \)=15cm

According to the question,

Area of the third square

= [\( \Large (17)^{2}-(15)^{2} \)]

= (17 + 15) (17 - 15)

= \( \Large 32\times 2 \)

= 64 sq cm

Let \( \Large a_{3} \) = Side of the third square

According to the question.

\( \Large (a_{3})^{2} \) = 64 sq cm

\( \Large a_{3} \) = \( \Large \sqrt{64} \) = 8 cm

Perimeter of the third square

= \( \Large 4\times a_{3}=4\times 8 \)=32cm