Answer:
Number 2: -3/10 (I think)
Number 4: 10a-5b-4
Number 6: x=5/2
Number 8: x=6
Explanation:
Number 2:
3ysquared/2y-4x2
3(-1)squared/2(-1)-4x2
3x1/2(-1)-4x2
3x1/-10
-3/10
(I might be wrong with this one though)
Number 4:
10a-3b-4-2b
10a-5b-4
Number 6:
2(-3x+8)=4x-9
-6x+16=4x-9
-6x+16-16=4x-9-16
-6x=4x-25
-6x-4x=4x-25-4x
-10x=-25
-10x/-10=-25/-10
x=5/2
Number 8:
1(4x-8)/4=-x+10
4x-8/4=-x+10
4x-8/4+x=-x+10+x
8x-8/4=10
4x8x-8/4=4x10
8x-8=4x10
8x-8=40
8x-8+8=40+8
8x=48
8x/8=48/8
x=6