Resposta :
Dobro 2x
Número x
Terça parte x
3
Agora vamos montar
2x+x=21
3 m.m.c
6x+1x=21
3
6x+1x=3.21
7x=63
x=63/7
x-9
Número x
Terça parte x
3
Agora vamos montar
2x+x=21
3 m.m.c
6x+1x=21
3
6x+1x=3.21
7x=63
x=63/7
x-9
2x+1/3=21 mmc de 1,3 = 3
6x/3+1/3=21
6x=21-1/3
6x= 63/3-1/3
6x=62/3
x=62/3/6
x=62/3.1/6
x=62/18
x=31/9
6x/3+1/3=21
6x=21-1/3
6x= 63/3-1/3
6x=62/3
x=62/3/6
x=62/3.1/6
x=62/18
x=31/9