烧杯 A 和烧杯 B 中装有一些水，如下图所示。烧杯 A 中的水比烧杯 B 中的水多多少升？

1. Determine the volume of water in Beaker A

The scale on Beaker A has 8 divisions up to $400\text{ ml}$.
Value of 1 division = $400 \div 8 = 50\text{ ml}$.
The water level is at the 7th mark.
Volume in Beaker A = $7 \times 50 = 350\text{ ml}$.

2. Determine the volume of water in Beaker B

The scale on Beaker B has 10 divisions up to $200\text{ ml}$.
Value of 1 division = $200 \div 10 = 20\text{ ml}$.
The water level is at the 8th mark.
Volume in Beaker B = $8 \times 20 = 160\text{ ml}$.

3. Calculate the difference in volume in millilitres

Difference = $350 - 160 = 190\text{ ml}$.

4. Convert the difference to litres

$190\text{ ml} = 190 \div 1000 = 0.19\text{ litres}$.