Question 638000
given:

angle {{{x=72}}}
find: the supplementary angle {{{y}}}

Supplementary angles are pairs of angles that add up to {{{180}}} degrees. Thus the supplement of an angle of {{{x}}} degrees is an angle of {{{y=(180-x)}}} degrees. 

{{{y=(180 -x)}}}...plug in {{{x}}}

{{{y=(180 -72)}}}

{{{y=108}}}degrees