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

Question

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

Answer 1

2/15×5/9+5/9×7/15=5/9(2/17+7/15)=
=5/9×9/15=1/3

11/18×9/34-7/18×9/34=9/34(11/18-7/18)=
=9/34×4/18=1/17

4/25×5/36+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