Answer:
\(3ax-by+c\)
a is the correct option.
Step-by-step explanation:
We have to find the sum of the polynomials ax + by + c, 2ax - 3by + c, and by - c .
Writing these polynomial in sum form
\(ax+by+c+2ax-3by+c+by-c\)
Group the like terms, we get
\((ax+2ax)+(by-3by+by)+(c+c-c)\)
Combine the like terms, we get
\(3ax-by+c\)
a is the correct option.
