Question 501361
An angle and its complement always have a sum of {{{90}}} degrees

the ratio of an angle to its complement is {{{2:7}}}...-> {{{alpha:(90-alpha)=2:7}}}

An angle and its supplement always have a sum of {{{180}}} degrees

you want to set this up as a proportion.

{{{2 / 7 = x / (90 -x)}}}

{{{2(90 -x) = 7x}}}

{{{180-2x =7x}}}

{{{9x = 180}}}

{{{x = 20}}}

{{{90 -20 = 70}}}

{{{70}}} degrees + it's supplement, {{{120}}} degrees exist in a {{{7:12}}} ratio

The compliment of {{{20}}} is {{{90-20}}} or {{{70}}} degrees

{{{20 / 70}}} is a ratio of {{{2:7}}}