To find the Greatest Common Factor (GCF) of the numerator and denominator of a fraction, we need to find the largest number that can divide evenly into both numbers.
To simplify the fraction 615, we need to find the GCF of 615 and 1.
The prime factorization of 615 is 3 x 5 x 41.
Since the GCF is the product of the common prime factors, the GCF of 615 and 1 is 1.
Therefore, the simplified fraction is Start Fraction 615 over 1 End Fraction, or simply 615.