-4|6b-8|<=12

Answer 1

-4|6b-8| ≤ 12
divide both sides by -4
|6b-8| ≥ -12
but by definition:
|6b-8| ≥ 0 <------ true for all values of b, no matter what is inside the |...| part

formal solution:
so 6b-8 ≥ 0 OR -6b + 8 > 0
b ≥ 4/3 or b ≤ 4/3 , so true for all values of b