Why is it difficult to cook on hills?

(N/A) At high altitudes,the atmospheric pressure is lower than at sea level.
According to the relationship between boiling point and pressure,the boiling point of water decreases as the external pressure decreases.
Consequently,water boils at a temperature lower than $100 \ ^\circ\text{C}$ on hills.
Since the food is cooked at a lower temperature,it does not receive sufficient heat energy to soften or cook properly in the same amount of time,making cooking difficult.