First we have to find the vertex (h,k) h is also x and it also is the a xis symmetry
1st: group the number
(X2+6x)-9
2nd: use b/2
6/2 = 3 , 3^2= 9
(X2+6x+9)-9-9
(X2 + 3)-18
Vertex is 3,-18 so the symmetry is 3
The 4 litres of red has to be 2 parts of the mixture, so each part will be 2 litres. Therefore 3 parts of cream will be 6 litres and the one part of blue will be 2 litres.
Cole's mistake was that he rounded 555 to the nearest hundred instead of the nearest ten. He should've rounded it to 560 because the tens place is the second number, not the first one.