I need help with these problems:

7) -a+2+a=-2a-6
9) -15+2x-8-6x=-x-2
10) x+8=2x+1
11) 8(2n-7) +7=-19+6n
12) -3(b+7)=-28-2b
13) -29-5x=7(8+x)-1
14) -5x+2(1-2x)=18+7x
15) 6-8n=6(1-5n)
16) -12+x=-4(-x-3)
17) 8(-5b+2)-4b=-4b-24
18) -5(p-1)=37-p
19) k-36=4(k-7)-5k
20) 2p-27=-3+8(-3-8p)
21) 3x-2/3--4/9 + 1/3x
22) 2/7x+x= -5/4x + 71/28
24) 2-x/2=-11/8x + 3/2
25) 2/3m-3=3/8m + 1/4m

If you were paying attention in class, you should have no problems doing these.
Multiply out and collect terms. When things move to the other side of the equal sign, they change sign. e.g. 2a=3a+1 --> 2a-3a=1
Collecting terms: (2-3)a=1 --> -a=1 -->
a=-1 (multiply both sides by -1)

5(3a+2) =0 --? 15a-10 =0 --> 15a=10
(solve for a is left as an excercise)

7. -a+2+a=-2a-6 combine like terms(-a+a=0)
2=-2a-6 combine like terms: add 6 to both sides
8=-2a divide -2 on both sides(8/-2 and -2/-2)
4=a


9. -15+2x-8-6x=-x-2 combine like terms(-15-8, 2x-6x)
-23-4x=-x-2 combine like terms by adding 4x on both sides
-23=3x-2 add 2 on both sides
-21=3x dived 3 on both sides
-7=x


10. x+8=2x+1 combine like terms: subtract 1 on both sides
x+7=2x combine like terms: subtract x on both sides
7=x



11. 8(2n-7)+7=-19+6n Distributive property(8*2n-8*7)
16n-56+7=-19+6n Subtract 56 from 7
16n-49=-19+6n combine like terms: add negative 19 on both sides
16n-30=6n Combine like terms: subtract 16n on both sides
-30=-10n Divide by -10 on both sides
3=n


Hopefully after seeing some of the problems done out you will be able to solve the others if not I will be glad to help you.

Algebra Elimination

I can't make it more easy than "KeepItSimpleStupid" explaned
Btw what sec. are you at?