To find the quotient of 5/31 divided by 15/23, first invert the divisor and multiply. This gives us (5/31) x (23/15). We can simplify this expression by canceling out the common factors of 5 and 15, which gives us (1/31) x (23/1) = 23/31. Therefore, the quotient of 5/31 divided by 15/23, reduced to the lowest fraction, is 23/31.