Answer:
The worker needs 3.74L of ingredient B
Explanation:
Given

Required
Determine the B equivalent of (1.3L + 0.5L) of A

Convert to Fraction

----(1)
For the new mix of A


New A requires New B:
So:
We have:

Convert this to fraction;
Substitut2 1.8L for New A
--- (2)
Equate (1) and (2)

Cross Multiply:

Divide through by 1.3


(Approximated)
Hence;
The worker needs 3.74L of ingredient B