kylechik19 1) 2(4,5 - 4x) = 7(2 - x)
9 - 8x = 14 - 7x
-8x + 7x = 14 - 9
-x = 5 | * (-1)
x = -5
2) 10(x + 1) = 2(3x + 3 2/9)
10x + 1 = 6x + 6 4/9
10x - 6x = 6 4/9 - 1
4x = 5 4/9
x = 5 4/9 : 4
x = 12,25

jekadva решите пропорцию
2/2-x=7/4.5-4x
2*(4,5-4x)=7*(2-x)
9-8x=14-7x
-8x+7x=14-9
-x=5
x=-5

и еще
12/x+1=10/3x+3 2/9
12*(3x+29/9)=10*(x+1)
36x+116/3 = 10x+10
36x-10x=10 - 116/3
26x = 30/3 - 116/3
26x= -86/3
x=-86/3*1/26
x= -43/39
x= -1 4/39