Question 614822
{{{(2^-1 - 2^-2)/(2^-3)}}}
rewrite it with two denominators
{{{(2^-1)/(2^-3)}}} - {{{(2^-2)/(2^-3)}}}
 subtract exponents when you divide like terms (this changes the signs of ^-3
{{{2^(-1+3))}}} - {{{2^(-2+3))}}}
:
2^2 - 2^1 
4 - 2 = 2