Ответ:

1) \(4,5+\frac12\cdot\frac{49}{20}:\frac{25}{12}-\frac95=\frac{411}{125}=3,288\).

2) \(1+\frac{160}{27}:\frac32=1+\frac{320}{81}=\frac{401}{81}=4\frac{77}{81}\).

3) \(1,8-\frac{13}{128}\cdot8=1,8-0,8125=0,9875\).

4) \(11-\frac{19}{20}:\frac15=11-\frac{19}{4}=\frac{25}{4}=6,25\).

Ответ: 1) 3,288; 2) \(4\frac{77}{81}\); 3) 0,9875; 4) 6,25.