The value at X.4 was +1 in the GMAC test and not -1 as shown.
Question:

+ X Y Z
4 -1 -5 M
E 7 n 10
F 2 -4 5

Or:

1: 3 ratio Concentrate: Water
200 * 6 Oz = 1200 total ounce of Juice containing proportionate 300 ounce concentrate

Therefore 300/12 = 25 cans of concentrate required