Question 103405
{{{80 + (1/2)H = H}}}
{{{80 + (1/2)H -(1/2) H= H - (1/2)H}}} Additive inverse of 1/2H

{{{80 =(1/2)H}}}

{{{2*80 =2*(1/2)H}}} Multiplicative inverse of 1/2. 
{{{H=160}}}