Question 198989
Let  x  =  amt  of  acid
.
.4(4) + .15x = .25(4+x)
.
1.6 + .15 x = 1 + .25x
.
.6 = .1x
.
x= 6 liters
.
check
.
.4(4) + .15(6) = .25(4 + 6)
1.6 + .9 = 2.5 ,,,,,ok