Answer:
(a) 
(b) The gravitational energy stored in the Great Pyramid of Cheops is
times greater than the daily food intake of a person (in Joules).
Explanation:
(a) Gravitational potential energy (with respect to the earth) is the energy possessed by an object due to its position from the surface of the earth.
It is given as:

where m = mass of object
g = acceleration due to gravity
h = height above the ground
∴ 
(b) A person's daily food intake = 2500 food calories
1 food calorie = 1000 regular calories
∴ 2500 food calories = 2500 * 1000 regular calories = 2500000 regular calories
We are given that :
1 regular calorie = 4.184 J
∴ 2500000 regular calories = 2500000 * 4.184 J = 
Comparing this with the answer in (a) above:

The gravitational energy stored in the Great Pyramid of Cheops is
times greater than the daily food intake of a person (in Joules).