f.2 maths quick`help me plz

1)Given y=1/1+x,find the value od x when y=3.

y=1/1+x
3=1/1+x
3(1+x)=1
3+3x=1
3x=1-3
3x= (-2)
x=( -2/3)

2)Given y=1/1-x,find the value of x when y=4.

y=1/1-x
4=1/1-x
4(1-x)=1
4-4x=1
-4x=1-4
-4x=-3
x=3/4

3)Given y=3x/x+2,find the value of x when y=2.

y=3x/x+2
2=3x/x+2
2(x+2)=3x
2x+4=3x
4=3x-2x
4=x

4)Given y=1+x/1-x,find the value of x when y=5.

y=1+x/1-x
5=1+x/1-x
5(1-x)=1+x
5-5x=1+x
5=1+x+5x
5=1+6x
5-1=6x
4=6x
4/6=x
x=2/3

1) y=1/1+x
3=1/1+x
1/3=1+x
x=1/3-1
x= -2/3

2) y=1/1-x
4=1/1-x
1/4=1-x
x=3/4

3) y=3x/ x+2
2 =3x/ x+2
2(x+2)=3x
2x+4=3x
2x-3x= -4
-x= -4
x=4

4) y=1+x/1-x
5=1+x/ 1-x
5(1-x) =1+x
5-5x=1+x
4=x+5x
6x=4
x=2/3