Question 1166227
let x equal the number of liters of the first solution.
let y equal the number of liters of the second solution.


you have 2 equations that need to be solved simultaneously.
they are:
x + y = 80
.18 * x + .43 * y = .265 * 80


multiply both sides of the first equation by .18 and simplify both equations to get:


.18 * x + .18 * y = 14.4
.18 * x + .43 * y = 21.2


subtract the first equation from the second to get:
.25 * y = 6.8
solve for y to get:
y = 6.8 / .25 = 27.2


since x + y = 80, then x must be equal to 80 - 27.2 = 52.8.
you have x = 52.8 and y = 27.2


x + y = 52.8 + 27.2 = 80 which is correct.
.18 * x + .43 * y = .18 * 52.8 + .43 * 27.2 = 21.2 which is correct.
21.2 / 80 = .265 = 26.5% which is also correct.


the solution is confirmed to be good.


your solution is that she needs to mix 52.8 liters of the 18% solution and 27.2 liters of the 43% solution to get a solution that an 80 liter solution that is 26.5% acid.