|x-y+3|与|x+y-99|互为相反数,求x-y除以x+y的值

|x-y+3|与|x+y-99|均为非负数
非负数的范围：正数和0
相反数的和为0
也就是|x-y+3|+|x+y-99|=0
x-y+3=0 ①
x+y-99=0 ②
由①得：x-y=-3 ③
由②得：x+y = 99 ④
③/④就得出x-y除以x+y的值
（x-y)/(x+y)=-1/33