I was with Tom 77, discovering that a Large tub was 0.7 litres, and a small tub was 0.55 litres. THEN, I got myself into a mig of a puddle.

She has 7 large tubs left, so that's 7x 0.7= 4.9 litres.

She has 2 small tubs left, so that's 2x 0.55= 1.1 litres

4.9 plus 1.1 = 6 litres.

And to double check ......

(12x 0.7) plus (8x 0.55) = 8.4 + 4.4 = 12.8 litres total volume. Subtract what's already made 12.8 - 6.8 = 6 litres.

Having now worked though the puzzle several times, I am once again embarrassed that I never learned my 7 times tables when I was in Primary School. I've got more chance of ordering a beer in Arabic.