It seems like you're trying to calculate the gravitational potential at a specific distance from the center of a planet. However, the information provided is a bit confusing. Here's a breakdown of what you've given and what's needed to solve the problem:

What you've given:

* Distance from the center of the planet (r): 7.2 x 10^7 m

* Planet's radius (R): 8.55 x 10^6 m

* An unknown value: 2.26 x 10^7 (It's unclear what this represents).

* A potential value: -5.6 (It's unclear what this represents).

What you need:

* Mass of the planet (M): This is crucial for calculating gravitational potential.

Here's how to calculate gravitational potential (V) at a distance (r) from the center of a planet:

1. Formula:

* V = -GM/r

* Where:

* G is the gravitational constant (6.674 x 10^-11 m^3 kg^-1 s^-2)

* M is the mass of the planet (in kg)

* r is the distance from the center of the planet (in meters)

2. Finding the mass (M):

* You can use the gravitational potential at the surface of the planet (-5.6 if that's the value you intended to provide) and the planet's radius to calculate the mass.

* -5.6 = -GM/R

* Solve for M: M = -5.6 * R / G

3. Calculate gravitational potential (V) at the specified distance (r):

* Use the calculated mass (M) and the provided distance (r) in the gravitational potential formula.

Example:

Let's assume the -5.6 is the gravitational potential at the surface of the planet.

1. Find the mass (M):

* M = -5.6 * (8.55 x 10^6 m) / (6.674 x 10^-11 m^3 kg^-1 s^-2)

* M ≈ 7.17 x 10^24 kg

2. Calculate gravitational potential (V) at r = 7.2 x 10^7 m:

* V = - (6.674 x 10^-11 m^3 kg^-1 s^-2) * (7.17 x 10^24 kg) / (7.2 x 10^7 m)

* V ≈ -6.68 x 10^6 J/kg

Important Note: This calculation assumes the gravitational potential at the surface is -5.6. Make sure to verify what this value represents before proceeding.

Please provide the correct value for the gravitational potential at the surface or the mass of the planet.