Starting from \((0,0)\) and moving east initially:
1) Move east \(80\) m: \((0,0) \to (80,0)\).
2) Turn right (south) and move \(50\) m: \((80,0) \to (80,-50)\).
3) Turn right (west) and move \(70\) m: \((80,-50) \to (10,-50)\).
4) Turn right (north) and move \(50\) m: \((10,-50) \to (10,0)\).
Distance from the origin \(=\) distance between \((0,0)\) and \((10,0)\) \(=\) \(\boxed{10\ \text{metres}}\).
% Topic - Direction & Distance