let the two compartments be C1, C2.
probability of getting coin from C1 = `1/2`
probability of getting coin from C2 = `1/2`
probability of getting 1 re coin from C1 = `2/5`
probability of getting 1 re coin from C2 = `3/5`
total probability = `1/2*(2/5) + 1/2*(3/5)