The answer is: " [tex]\frac{1}{2}[/tex] x − 6 " ._______________________________________________ → in which "x" represents the "unknown number" . _______________________________________________The expression written for: "Half of a number decreased by 6" is: → " [tex]\frac{1}{2}[/tex] x − 6 " ; _____________________________________________ → in which "x" represents the "unknown number" .________________________________________Explanation:Let "x" represent the "unknown number". → "One-half" of a number , decreased by "6" ; → is written as: "1/2 of "x" , minus "6" .Note that: " 1/2 of x " = " [tex]\frac{1}{2}[/tex] * x " = " [tex]\frac{1}{2}[/tex] x " .Then, we subtract "6" ; from that value; to write the expression:________________________________________The expression written for: "Half of a number decreased by 6" is: " [tex]\frac{1}{2}[/tex] x − 6 " ; → in which "x" represents the "unknown number" .________________________________________Hope this helps!Best wishes in your academic endeavors — and within the "Brainly" community!________________________________________