3070кг= т кг 6 км. 015м = м с р ч н о ! ! !

3070 кг = 3 т 070 кг 6 км 015 м= 6015 м

3070кг=3т 70кг 6км 015м=6015м

1)
1 1/12 + 3 3/4 + x = 4 1/2
1 1/12 + 3 9/12 + x = 4 1/2
4 10/12 + x = 4 1/2
x = 4 1/2 - 4 5/6
x = - (4 5/6 - 4 3/6)
x = - 2/6 
x = -1/3

2)
-( 5 2/3 - 1 3/5) - x = 6 1/3
-(5 10/15 - 1 9/15) - x = 6 1/3
-4 1/15 - x = 6 1/3
x = -(6 1/3 + 4 1/15)
x = -(6 5/15 + 4 1/15)
x = - 10 6/15
x = -10 2/5

3)
x - (7 10/18 - 5 3/18) = -3 1/2
x - 2 7/18 = -3 1/2
x = -(3 1/2 - 2 7/18)
x = -(3 9/18 - 2 7/18)
x = -1 2/18
x = -1 1/9

4)
x - (-4 3/5 + 3 4/7) = -8 1/14
x + 4 21/35 - 3 20/35 = -8 1/14
x + 1 1/35 = -8 1/14
x = -(8 1/14 + 1 1/35)
x = -(8 5/70 + 1 2/70)
x = -9 7/70
x = -9 1/10

20*9-3x=100-1
180-3x=99
180-99=3x
3x=81
x=81:3=27

78 *(49+51)-69*(36+64)=78*100-69*100=100*9=900