Question 350269
1.{{{A+S=180}}}
2.{{{A+C=90}}}
3.{{{S=7C}}}
Subtract eq. 1 from eq. 2,
{{{A+S-A-C=180-90}}}
{{{S-C=90}}}
Substitute from eq. 3,
{{{7C-C=90}}}
{{{6C=90}}}
{{{C=15}}}degrees
Then from eq. 3,
{{{highlight(S=105)}}}degrees