Final answer:
For the given set of equations, substitution is more convenient since one equation is already solved for y, allowing us to easily substitute this into the other equation to solve for x. Option b is correct.
Step-by-step explanation:
To decide whether it would be more convenient to solve the system of equations by substitution or elimination, let's evaluate the given equations:
-10x - 13y = -9
y = -6x - 9
Since the second equation has already been solved for y, it is straightforward to use the substitution method. We can substitute -6x - 9 in place of y in the first equation to find the value of x:
-10x - 13(-6x - 9) = -9
After finding x, we can plug this value back into the second equation to find y.
While elimination might also be possible, the coefficients of x and y are not multiples of each other, which makes it less convenient compared to substitution. Thus, for this set of equations, substitution is the more suitable method.