[tex]x-\ Kathryn's\ points\\\\
y-\ Michael's\ points\\\\
\left \{ {{x+y=425} \atop {y+70=2x\ \ | subtract\ 70}} \right. \\\\ \left \{ {{x+y=425} \atop {y=2x-70}} \right. \\ substitution\ method\\\\
x+2x-70=425\\\\
3x-70=425\ \ | add\ 70\\\\
3x=495\ \ \ | divide\ by\ 3\\\\
x=165\\\\
y=2x-70=2*165-70=330-70=260\\\\
Kathryn\ scored\ 165\ points\ and\ Michael\ 260[/tex]
