Question 1152931
x amount of water
400 ml * 0.16 saline=64 ml pure saline
add x water
(400+x)(0.10)=64 ml pure saline.  Here, we know that if we add the right x of water, the whole solution will be 400+x ml, but the per cent will be 10

40+.10x=64
.10x=24
x=240 ml