Since x and y are in the ratio 5 to 2, x = 5a and y = 2a, for some positive number, a.
Since y and z are in the ratio 8 to 11, y = 8b and z = 11b, for some positive number, b.
So, since y = 2a and y = 8b, 2a = 8b. Therefore, a = 4b.
We then have x = 5a = 5(4b) = 20b
y = 8b
z = 11b
We know that x+y+z =78
So, 20b + 8b + 11b = 78
39b = 78
b = 2
Thus, x = 20b = 40 liters
y = 8b = 16 liters
z = 11b = 22 liters
ANDREA S.
11/29/16