Question 1010109
x ml 0.20 acid
360 ml 0.90 acid
they equal (360+x)0.40 acid
0.2x+324=144_0.40x
-0.2x=-180
x=900 ml of 20% acid
This should be a 5/2 ratio, since 40% is 2/5 of the way from 20% to 90%
900 is 5/2 360.