8. The points \(P\) and \(Q\) have coordinates \(( 7,4 )\) and \(( 9,7 )\) respectively.
- Find an equation for the straight line \(l\) which passes through \(P\) and \(Q\). Give your answer in the form \(a x + b y + c = 0\), where \(a , b\) and \(c\) are integers.
The straight line \(m\) has gradient 8 and passes through the origin, \(O\).
- Write down an equation for \(m\).
The lines \(l\) and \(m\) intersect at the point \(R\).
- Show that \(O P = O R\).