Final answer:
The sum of the fractions 15x/16 and 19/16 is (15x + 19)/16, as they have the same denominator. This is the solution in the lowest terms and matches option a.
Step-by-step explanation:
To add the fractions 15x/16 and 19/16, since they have a common denominator, you simply add the numerators together. This calculation will yield a new fraction with the same denominator of 16.
The sum of the two fractions is:
(15x/16) + (19/16) = (15x + 19)/16
There is no further simplification possible, as 15x + 19 does not share a common factor with 16 other than 1. Therefore, the solution in lowest terms is indeed (15x + 19)/16, which corresponds to option a.