1) (34,2-x) : 8,7 = 2,3

2) 12,76 + (48,93-x) : 4,2 = 18,86

34.2-x=2.3*8.7=20.01

x=34.2-20.01=14.19

проверка:

(34.2-14.19) = 20.01

20.01:8.7=2.3

2.3=2.3

Ответ:x=14.19

б) (48.93-x) : 4.2=18.86-12.76

(48.93-x) : 4.2=6.1

48.93-x=6.1*4.2

48.93-x=25.62

x=48.93-25.62=23.31

проверка:

(48.93-23.31) = 25.62

25.62:4.2=6.1

12.76+6.1=18.86

18.86=18.86

Ответ:x=23.31