The force of gravity is that amount of attractive force which is exerted between two bodies on each other.
As per Newton's law of gravitation the force of gravity is directly proportional to the product of the masses of the two bodies and inversely proportional to the square of separation distance between them.
Mathematically
Here G is the gravitational constant whose value is 6.67×
As per the question the masses of the objects are increased keeping the separation distance same.
As force of gravity ∝ product of masses of two bodies,
Hence the force of gravity increases with the increase of mass.