The Coulomb’s law is expressed mathematically as:
F = k * q1 * q2 / d^2
Where,
F = force of attraction between 2 particles = 2.0 N
k = Coulomb’s constant = 8.988 * 10^9 N m^2 / C^2
q = charge of the particle
d = distance between the 2 particles = 1.35 m
Since the two coins have identical charges therefore q1 = q2 =q
F = k* q^2 / d^2
2.0 N = (8.988 * 10^9 N m^2 / C^2) * q^2 / (1.35 m)^2
q = 2.01 * 10^-5 C
Therefore each coins have charges equivalent to 2.01 * 10^-5 C.