A flat aluminium plate is acted on by two mutually perpendicular stresses, s[SUB]x[/SUB] and s[SUB]y[/SUB]. The resulting strains are e[SUB]x[/SUB] = 4.2x10[SUP]-4[/SUP] and e[SUB]y[/SUB] = 9.0x10[SUP]-5[/SUP]. Given E = 70GPa and n=0.33, find the values of the stresses.