Question 963285
The angles sum to 180.
{{{C+x=90}}}
{{{C=90-x}}}
.
.
{{{S+x=180}}}
{{{S=180-x}}}
.
.
{{{x+2C+S/8=180}}}
{{{8x+16C+S=1440}}}
{{{8x+16(90-x)+180-x=1440}}}
{{{8x+1440-16x+180-x=1440}}}
{{{-9x+180=0}}}
{{{x=highlight(20)}}}
Then,
{{{2C=2(90-20)=highlight(140)}}}
and,
{{{S/8=180-x-2C=180-20-140=highlight(20)}}}