Question 340644
1.{{{A+C=90}}}
2.{{{A+S=180}}}
3.{{{S=6C}}}
Subtract eq. 1 from eq. 2,
{{{A+S-A-C=180-90}}}
{{{S-C=90}}}
Substitute from eq. 3,
{{{6C-C=90}}}
{{{5C=90}}}
{{{highlight(C=18)}}}degrees
Then 
{{{S=6(18)}}}
{{{highlight(S=108)}}}degrees
.
.
.
{{{A=90-18}}}
{{{highlight(A=72)}}}degrees