Answer:
Simplifying 
x = -25
Explanation:
Reorder the terms: 
10x + -6(5 + 2x) = 20 
10x + (5 * -6 + 2x * -6) = 20 
10x + (-30 + -12x) = 20 
Reorder the terms: 
-30 + 10x + -12x = 20 
Combine like terms: 10x + -12x = -2x 
-30 + -2x = 20 
Solving 
-30 + -2x = 20 
Solving for variable 'x'. 
Move all terms containing x to the left, all other terms to the right. 
Add '30' to each side of the equation. 
-30 + 30 + -2x = 20 + 30 
Combine like terms: -30 + 30 = 0 
0 + -2x = 20 + 30 
-2x = 20 + 30 
Combine like terms: 20 + 30 = 50 
-2x = 50 
Divide each side by '-2'. 
x = -25