Question 342561
{{{A+S=180}}}
.
.
{{{A=3S-20}}}
Substitute,
{{{3S-20+S=180}}}
{{{4S-20=180}}}
{{{4S=200}}}
{{{highlight(S=50)}}}degrees
.
.
.
{{{A=3(50)-20}}}
{{{A=150-20}}}
{{{highlight(A=130)}}}degrees