Question 345421
1.{{{A+C=90}}}
2.{{{A+S=180}}}
3.{{{S=10+3C}}}
Subtract eq. 1 from eq. 2,
{{{A+S-A-C=180-90}}}
{{{S-C=90}}}
Now substitute from eq. 3,
{{{10+3C-C=90}}}
{{{2C=80}}}
{{{highlight(C=40)}}}degrees
.
.
{{{S-40=90}}}
{{{highlight(S=130)}}}degrees
.
.
{{{A+130=180}}}
{{{highlight(A=50)}}}degrees