SOLUTION: I am looking for help, I don't really understand how to solve these equation. 1) 10n+5n-6=9 2) 25=19+20n-18n 3) 3/1/2r+r+2=20 4) 5r=2r+27 5) 100+3/1/2t=23/1/2t 6) 9u=16u-10

Algebra ->  Expressions -> SOLUTION: I am looking for help, I don't really understand how to solve these equation. 1) 10n+5n-6=9 2) 25=19+20n-18n 3) 3/1/2r+r+2=20 4) 5r=2r+27 5) 100+3/1/2t=23/1/2t 6) 9u=16u-10      Log On


   



Question 663730: I am looking for help, I don't really understand how to solve these equation.
1) 10n+5n-6=9
2) 25=19+20n-18n
3) 3/1/2r+r+2=20
4) 5r=2r+27
5) 100+3/1/2t=23/1/2t
6) 9u=16u-105
7) 5x+3-2x=x+8

Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
1) 10n+5n-6=9
Combine like terms
15n - 6 + 6 =9+6
15n=15
n=1
...
2)25=19+20n-18n
Combine like terms
25-19=19+2n-19
6 = 2n
n = 3
...
3)3/1/2r+r+2=20
(3/1/2)r = 3/1 is 3 so (3/1/2)r = 3/2r
3/2r + r + 2 = 20
Combine like terms
3/2r + r + 2 - 2 = 20 - 2
3/2r + r = 18
Multiply both sides by 2
3r + 2r = 18*2
5r = 36
r = 36/5 = 7.2
...
4)5r=2r+27
Subtract 2r from both sides to isolate r
5r-2r=27
Combine like terms
3r=27
Divide both sides by 3
r=9
...
5) 100+3/1/2t=23/1/2t
3/1/2t where 3/1 is 3 so 3/1/2t is 3/2t
23/1/2t where 23/1 is 23 so 23/1/2t is 23/2t
100 + 3/2t = 23/2t
Group like terms
3/2t - 23/2t = -100
Multiply both sides by 2
3t - 23t = -200
-20t = -200
Divide both sides by -20
t=10
...
6)9u=16u-105
Group like terms
9u - 16u = -105
-7u = -105
u = 15
...
7)5x+3-2x=x+8
5x-2x-x = -3 + 8
2x = 5
x = 5/2 = 2 1/2 = 2.5
............
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