1) 34 · (−4); 2) −7,2 · (−7); 3) −3 1/5 · 1 2/3; 4) −3 5/9 · (−1 1/8).

1. \(34 \cdot (-4) = -136\).
2. \((-7.2) \cdot (-7) = 50.4\).
3. \(-3\frac{1}{5} \cdot 1\frac{2}{3} = -\frac{16}{5} \cdot \frac{5}{3} = -\frac{16}{3} = -5\frac{1}{3}\).
4. \(-3\frac{5}{9} \cdot \left(-1\frac{1}{8}\right) = -\frac{32}{9} \cdot \left(-\frac{9}{8}\right) = 4\).

Ответ: 1) −136; 2) 50,4; 3) −5 1/3; 4) 4.