A rectangular plate of dimensions $100mm250mm$ is formed by welding two triangular plates, as shown in the diagram below. The plate is subjected to a tensile stress of $12\mathrm{.}0$MPa in the short direction and a compressive stress of $2\mathrm{.}5$MPa in the long direction. Determine the normal stress ${}_w$ acting perpendicular to the line of the weld and the shear stress ${}_w$ acting parallel to the weld.