The problem asks us to find the size of angle $g$ in a pie chart where the other two angles are $100^{\circ}$ and $140^{\circ}$.

1. Problem Description

The problem asks us to find the size of angle $g$ in a pie chart where the other two angles are $100^{\circ}$ and $140^{\circ}$.

2. Solution Steps

The sum of angles in a full circle is $360^{\circ}$.

Therefore, the sum of all angles in the pie chart must be equal to $360^{\circ}$.

$g + 100^{\circ} + 140^{\circ} = 360^{\circ}$

$g + 240^{\circ} = 360^{\circ}$

$g = 360^{\circ} - 240^{\circ}$

$g = 120^{\circ}$

3. Final Answer

The size of angle $g$ is $120^{\circ}$.