First calculate the diagonal of the square using this formula:
[tex] a * \sqrt{2} [/tex] where a = one of the sides.
Formula in our situation:
[tex] 150 * \sqrt{2} [/tex]
150 * 1,414213562373095
213 yards (212.13)
Answer:
[tex] \boxed{\bf~John~will~need~213~yards~of~fence.} [/tex]
Hope it helped,
Happy homework/ study/ exam!