To find the solution to the given equation, let's simplify it:

Combining like terms:

Dividing both sides by 26:
![\[x = -(18)/(26) = -(9)/(13)\]](https://img.qammunity.org/2024/formulas/mathematics/high-school/zgd3h6jrd6q7lri5yj57i4ps2wkfgs36ve.png)
So, none of the provided answer choices A, B, C, or D contains the correct solution. The correct answer would be

The probable question maybe:
Given the equation 5x + 21x = -18, which solution set accurately satisfies the equation?
A. -5/6 and 3
B. -6/5 and -3
C. 2 and 1
D. 3 and 4