ƚ U E .  & & MathType-@(Times New Roman؟ww wm f-2 `xy2 `|xyTimes New Roman؟ww wm f-2 `*2y2 6y2 n1y2 Z3y2 nZ2ySymbol >؟ww wm f-2 `=y2 `x-y & "Systemm f !-