Question 905719
{{{A+S=180}}}
{{{S=3A-10}}}
Substitute,
{{{A+(3A-10)=180}}}
{{{4A-10=180}}}
{{{4A=190}}}
{{{highlight(A=95/2)}}}
Then,
{{{S=3(95/2)-10}}}
{{{S=285/2-20/2}}}
{{{highlight(S=265/2)}}}