How will the force of mutual attraction of two balls change if the distance between them is increased by 3 times?

The force of attraction of two balls to each other:
F = G * m1 * m2 / R², where G is the gravitational constant, m1 is the mass of the first ball, m2 is the mass of the second ball, R is the distance between the balls.
The force of mutual attraction of the balls before changing the distance:
F1 = G * m1 * m2 / R1².
The force of mutual attraction of the balls after increasing the distance by 3 times:
F2 = G * m1 * m2 / R2², where R2 = 3R1.
F2 / F1 = (G * m1 * m2 / R2²) / (G * m1 * m2 / R1²) = R1² / (3R1) ² = 1/9.
Answer: The force of mutual attraction will decrease by 9 times.