The ratio is 2.3:1.2 for A:B. Ratios will remain the same but can be scaled up or down by some factor/multiple. Like if you had a food recipe that you needed to double, the scaling factor would be 2 and all ingredients in the recipe would be doubled.
Since we don't know the scaling factor, we assign that multiple "x". Then the amounts of each ingredient oil would be:
amount of A = 2.3x
amount of B = 1.2x
add them together to get the required mixture amount.
1000 = 2.3x + 1.2x
1000 = 3.5x
1000/3.5 = x
285.7 = x
this is the scaling factor.
plug x in to find the amounts of each oil type.
A = 2.3(285.7)
A = 657.1 L
B = 1.2(285.7)
B = 342.9 L