3)
5и7=6
5,7и 9=7
Извини 2-ое незнаю
A = 40; a+347 = 387; a-39 = 1
a = 53; a+347 = 400; a-39 = 14
a = 282; a+347 = 629; a-39 = 243
a = 558; a+347 = 905; a-39 = 519
1. (27/28-5/9)-(-(1/28)+(8+4/9))=-8
1. 27/28-5/9=243/252-140/252=103/252
2. -(1/28)+(8+4/9)=-(9/252)+(8+112/252)=8+103/252
3. 103/252-(8+103/252)=-8
2. -(-(20/27)+3/8)+(-(5+5/8)+(4+7/27))=-1
1. -(20/27)+3/8=-(160/216)+81/216=-(79/216)
2. -(5+5/8)+(4+7/27)=-(5+135/216)+(4+56/216)=-(1+79/216)
3. -(-(79/216))+(-(1+79/216))=79/216-(1+79/216)=-1
Ответ:
34 2/3:8/15=104/3:8/15=104:8*15:3=13*5=65