Question 127999
An ordered pair is a value of x paired with a value for y.  An ordered pair is a member of the solution set of an equation if and only if the replacement of x and y in the equations by the values given in the ordered pair make the equation a true statement.  An ordered pair is a member of the solution set of a <i><b>system</i></b> of two equations in two variables if and only if the values for x and y make <i><b>both</i></b> of the equations true statements.


(-2,15) is the given ordered pair.  {{{red(-2)}}} is the x-coordinate value, and {{{green(15)}}} is the y-coordinate value.  We know that because they are always in that order, hence the term 'ordered pair.'


{{{y = -3x + 9}}}:  Replace x and y with the given coordinate values:
{{{cartoon(green(y)= -3*red(x) + 9,green(15)=-3*red((-2))+9)}}}


Is {{{15=-3(-2)+9}}} a true statement?


{{{y = 5x + 25}}}:  Replace x and y with the given coordinate values:
{{{cartoon(green(y) = 5*red(x) + 25,green(15)=5*red((-2))+25)}}}


Is {{{15=5(-2)+25}}} a true statement?


If the answer to <i><b>both</i></b> questions is YES, then the given ordered pair is a member of the solution set.


If the answer to either or both questions is NO, then the given ordered pair is NOT a member of the solution set.


I'll leave it to you to do the arithmetic and decide.