A steel plate having yield strength of \( 550 \) MPa is subjected to a biaxial state of stress as \( \sigma_x = \sigma \) and \( \sigma_y = -2\sigma \). Using the distortion energy theory (von Mises criterion) and taking the factor of safety as \( 2 \), find the permissible value of \( \sigma \) that can be applied to the plate. Give the answer in MPa, rounded off to 1 decimal place.