Vector upper a overscript right-arrow endscripts has a magnitude of 69 units and points due west, while vector upper b overscript right-arrow endscripts has the same magnitude and points due south. find the magnitude and direction of (a) upper a overscript right-arrow endscripts plus upper b overscript right-arrow endscripts and (b) upper a overscript right-arrow endscripts minus upper b overscript right-arrow endscripts. specify the directions relative to due west.