Question 773409
Supplementary angles are pairs of angles that add up to {{{180}}} degrees.

let one angle be {{{alpha}}} and its supplementary angle {{{beta}}}

 if {{{alpha}}} is {{{12}}} degrees less than three times its supplement {{{beta}}}, then we have  {{{alpha=3beta-12}}}

so,{{{alpha+beta=180}}}.....substitute {{{alpha=3beta-12}}}

{{{3beta-12+beta=180}}}.......solve for {{{beta}}}

{{{4beta=180+12}}}

{{{4beta=192}}}

{{{beta=192/4}}}

{{{beta=48}}}

then {{{alpha=3beta-12}}}=> {{{alpha=3*48-12}}}=>{{{alpha=132}}}