Question 132257
{{{(3.99-X)/3.5=1.35/1}}}
use the following formula if {{{a/b=c/d}}} then {{{ad=bc}}} 
so {{{(3.99-X)=3.5(1.35)}}}
{{{3.99-X=4.725}}}
{{{3.99-4.725=X}}}
{{{X=-0.735}}}