1) $$\frac{15}{34} \cdot \frac{68}{125} = \frac{15 \cdot 68}{34 \cdot 125} = \frac{15 \cdot 2 \cdot 34}{34 \cdot 125} = \frac{15 \cdot 2}{125} = \frac{30}{125} = \frac{6}{25}$$
2) $$\frac{23}{244} \cdot \frac{12}{69} = \frac{23 \cdot 12}{244 \cdot 69} = \frac{23 \cdot 12}{4 \cdot 61 \cdot 3 \cdot 23} = \frac{12}{4 \cdot 61 \cdot 3} = \frac{12}{12 \cdot 61} = \frac{1}{61}$$
3) $$54 \cdot \frac{17}{27} = \frac{54 \cdot 17}{27} = \frac{2 \cdot 27 \cdot 17}{27} = 2 \cdot 17 = 34$$
Ответ:
1) $$\frac{6}{25}$$
2) $$\frac{1}{61}$$
3) $$34$$