Question 751356
{{{100+x<=41-6x <=121+x}}}.....add {{{-x}}} to all


{{{100+x-x<=41-6x-x <=121+x-x}}}

{{{100+cross(x)-cross(x)<=41-6x-x <=121+cross(x)-cross(x)}}}


{{{100<=41-6x-x <=121}}}....add {{{-41}}} to all


{{{100-41<=41-41-7x <=121-41}}}


{{{59<=cross(41)-cross(41)-7x <=80}}}


{{{59<=-7x <=80}}}....divide all by {{{7}}} 


{{{59/7<=-7x/7 <=80/7}}}....multiply all by {{{-1}}}


{{{-59/7<=x <=-80/7}}}

or

{{{-8.43<=x <=-11.43}}}