Question 888903
Let Peter's age be "p"
    Chantal's age be "c"

A. System of Linear Equations
{{{p = 6 + c }}} ---> First Equation
{{{p + c = 60}}} ---> Second Equation

B. Substitution
{{{6 + c + c = 60}}}
{{{2c = 54 }}}
{{{c = 27 }}}
{{{ p = 6 + (27)}}}
{{{ p = 33 }}}

Therefore, Peter's age is 33 and Chantal's age is 27.