1、用水:500x(1-5%)=475(克) 用盐:500x5%=25(克) 2、加盐: 500x(1-5%)÷(1-15%)-500 =475÷0.85-500 =558.82-500 =58.82(克) 3、5%的用量为: (5000x15%-5000x12%)÷(15%-5%) =150÷10% =1500(克) 15%的用量为: 5000-1500=3500(克)