14/4=3 2/4
3 2/4 - 2 4/5 = 3 10/20 - 2 16/20 = 2 30/20 - 2 16/20 = 14/20
1.
1) -b-c
2)-a+b+c
3) a-b-c
2.
1)-b+c
2)a+b-c
3)-a-b+c
0.(7) = x
10x = 7.(7)
10x - x = 7.(7) - 0.(7)
9x = 7
x = 7/9
==========
x = 2.4(3)
10x = 24.(3)
100x = 243.(3)
100x - 10x = 243.(3) - 24.(3)
90x = 219
x = 219/90 = 73/30
18:2=9
Ответ:9 мальчиков
в классе