Answer
9 times more.
Work Step by Step
The pressure on each piston is the same.
$$\frac{F_{small}}{small \;area} = \frac{F_{large}}{large\; area}$$
$$\frac{F_{large}}{F_{small}} = \frac{large \;area}{small\; area}$$
The ratio of areas is the ratio of the squares of the diameters. $\frac{6^{2}}{2^{2}} = 9$. The force on the large piston is 9 times the force on the small piston.
This is discussed on page 255.
