Question 343912
NEED TO KNOW:
BY DEFINITION THE SUM OF SUPPLEMENTARY ANGLES IS 180 DEGREES!
{{{S[1]+S[2]=180}}} 
THE QUESTION STATES THE FOLLOWING TO BE TRUE:
{{{S[1]= 2(S[2])+3}}}
SUBSITUTE
{{{(2(S[2])+3)+S[2]=180}}} 
{SOLVE:
{{{2(S[2])+3+S[2]=180}}} 
COMBINE
{{{(3(S[2])+3)=180}}}
SIMPLY: SUBTRACT 3 FROM EACH SIDE OF THE EQUATION
{{{3(S[2])=177}}}

DIVIDE EACH SIDE OF THE EQUATION BY 3
{{{S[2]=59}}} THE MEASURE OF THE ANGLE!!
{{{S[1]= 2*59+3}}}
{{{S[1]= highlight(121)}}} THE MEASURE OF THE ANGLE IN QUESTION
CHECK YOUR ANSWER!!  
59-121 = 180