Sally drives a mini school bus. She starts from the school gate and drives $7\text{km}$ North to pick up her first ride. Then she turns right and drives $10\text{km}$ picking up children along the way. She takes another right turn and drives $5\text{km}$. She then takes a final right turn to return to the school. How far would Sally need to drive to reach back to the school gate again?

Let's trace Sally's journey step-by-step from the starting point (School Gate), assuming it is at coordinates $(0,0)$:
1. Initial position: School Gate at $(0,0)$.
2. First leg (North): Drives $7\text{km}$ North $⟹$ reaches point $(0,7)$.
3. **Second leg (Right turn $\to$ East):** Turns right and drives $10\text{km}$ East $⟹$ reaches point $(10,7)$.
4. **Third leg (Right turn $\to$ South):** Turns right and drives $5\text{km}$ South $⟹$ reaches point $(10,7-5)=(10,2)$.
5. **Final leg (Right turn $\to$ West):** She takes a final right turn, which faces her towards the West direction to align back to the school path.

To return to the school gate at $(0,0)$ from her current position $(10,2)$ along the grid lines:

* She needs to drive $10\text{km}$ West to reach the vertical axis alignment of the school gate: $(10,2)\to (0,2)$, which takes $10\text{km}$.
* From $(0,2)$, she needs to drive $2\text{km}$ South to reach the school gate at $(0,0)$: which takes $2\text{km}$.

$$\text{Total distance to drive}=10\text{km}+2\text{km}=12\text{km}$$

Therefore, Sally needs to drive $12\text{km}$ to reach back to the school gate.