Explanation:
Assuming all of the figures are squares ......
find the side lengths of the red and green squares:
46 m^2 = r^2
r = sqrt (46) meter side length
38 m^2 = g^2
g = sqrt (38) meter side length
Now find blue side length using Pythagorean Theorem:
b^2 = sqrt(46)^2 + sqrt(38)^2
b^2 = 46 + 38
b side length = sqrt(84) meter
area of blue = blue side X blue side = sqrt(84) * ( sqrt 84) = 84 m^2