Применяя законы и свойства арифметических действий, упростите выражение:
1) 3a+3(1+a);
3) 5(m+3n)+2(2m-n);
5) 7(2x+3y)-3(3x+2y);
9) 9(a-2b)-10(3a+b);
11) 6(2x-y)-5(3x-2y)

1. Who lives in the river? 2.what does the Frog like very much? 3.Do the ducks like winter? Why? 4. Why do the ducks take the Frog with them ? 5. what do the birds say to the Frog? 6. What do the children see in the sky? 7. What season is it in the text? Do you like this season? Why? Why not? нужны ответы