Let's first simplify the equation by distributing the 5 on the left side:

5(-10) - 5(2x) = -3x + 26
-50 - 10x = -3x + 26

Next, let's combine like terms on the left side:

-10x - 50 = -3x + 26

Now, let's move all the terms involving x to one side of the equation. We can do this by adding 3x to both sides and adding 50 to both sides:

-10x + 3x - 50 = -3x + 3x + 26 + 50
-7x - 50 = 76

Finally, let's solve for x by adding 50 to both sides and then dividing by -7:

-7x = 126
x = -126/7
x = -18