Question 621749
{{{-1 <= 2x+1 <= 3}}}
break into two halves
{{{-1 <= 2x+1}}} and {{{2x+1 <= 3}}} now solve each separately
{{{-1 <= 2x+1}}}
{{{-2 <= 2x}}}
{{{-1 <= x}}}
and {{{2x+1 <= 3}}}
{{{2x<= 2}}}
{{{x <=1}}}
now put them back together
{{{-1 <= x <= 1}}}