Answer:
4.243
Step-by-step explanation:
To calculate the diagonal of a square, multiply the length of the side by the square root of 2:
d = a√2
d = 3√2=4.24264068
x + 2y = 10 ⇒ 2y - 10 = -x
-x + 4y = 14
2y - 10 + 4y = 14
6y = 24
y = 4
I think the answer is the third one
B