Question 210328
Complimentary angles add to be 90 degrees 
Supplimentary angles add to be 180 degrees

let original angle = o
let compliment of original angle = c
let supplement of original angle = s
o+c=90
o+s=180

20+2c=s
This can be put in terms of the original angle (o) by rearranging the above equations.
{{{c=90-o}}}
{{{s=180-o}}}
substitute these into {{{20+2c=s}}}
so {{{20+2(90-o)=180-o}}}
{{{20+180-2o=180-o}}}
{{{20-2o=-o}}}
{{{20=o}}}
Therefore, {{{c=70}}} and {{{s=160}}}

Check your answer:
Is 160=70*2+20    Yes