Найдите значение выражения:
1) 2/15*5/9+5/9×7/15
2) 11/18×9/34-7/18*9/34
3) 4/25*5/36+18/25*5/36-9/25*5/36+1/25*5/36

2/15×5/9+5/9×7/15=5/9(2/17+7/15)==5/9×9/15=1/311/18×9/34-7/18×9/34=9/34(11/18-7/18)==9/34×4/18=1/174/25×5/36+18/25×5/36-9/25×5/36+1/25×5/36==5/36(4/25+18/25-9/25+1/25)=5/36×14/25==1/5×7/18=7/90