60*4%=2.4 (kg)

2.4/5%=48 (kg)

60-48= 12

Answer: Take 48kg B saline and add 12kg water.

60*4%=2.4 (kg)

2.4/6%=40 (kg)

60-40 = 20kg

Answer: Take 40kg of saline C and add 20kg of water.

(2):

Let 2% salt water take X kg and 6% salt water (60-x).

2%x + 6%(60-x) = 60 * 4%

x = 30

Answer: 30 kg of 2% and 6% saline respectively.