Question 334160
1.{{{A+C=90}}}
2.{{{A+S=180}}}
3.{{{C=(1/4)S}}}
Subtract eq. 1 from eq. 2,
{{{A+S-A-C=180-90}}}
{{{S-C=90}}}
Substitute eq. 3,
{{{S-S/4=90}}}
{{{(3/4)S=90}}}
{{{S=120}}}degrees
{{{C=S/4=30}}}degrees
{{{A=90-C=60}}}degrees