小六方程 幫我解答啦!

1.5(2B+3)=15
10B+15=15
B=0
2.7X+3=9X-7
10=2X
X=5
3.K-Kx30%=28
(7/10)K=28
K =40
4.50-y=4(17-Y)
50-y=68-4Y
3Y=18
Y=6
5.R+Rx20%=36
120%R=36
R= 30
6.K/5+K/3=16
8K/15=16
8K=120
K=15
7. Px30%+Px50%=24
80%P=24
P=2400/80
P=30
8. P/3-P/5=16
-5P/15=16
-5P=90
P= -18

2008-03-30 02:10:50 補充：
第六和第八我錯左,,,,
should be like this:

6.K/5+K/3=16
8K/15=16
8K=240
K=30

8. P/3-P/5=16
2P/15=16
2P=240
P=120

1. 5(2B 3)=15
2B 3 =15/5
2B 3 =3
2B =3-3
2B =0
B =0/2
B =0

2. 7X 3=9X-7
3=9X-7-7X
3 7=2X
2X=10
X=10/2
X=5

3. K-Kx30%=28
K-0.3K=28
0.7K=28
K=28/0.7
K=40

4. 50-y=4(17-Y)
50-y=4x17-4y
50=68-4y y
3y=18
y=6

5. R Rx20%=36
R 0.2R=36
1.2R=36
R=36/1.2
R=30

6. K/5 K/3=16
3K/15 5K/15=16
8K/15=16
8K =16x15
K =30

7. Px30% Px50%=24
0.3P 0.5P=24
0.8P=24
P=24/0.8
P=30

8. P/3-P/5=16
5P/15-3P/15=16
2P/15=16
2P=16x15
2P=240
P=120

1. 5(2B+3)=15 ==> 2B+3=3 ==> 2B=0 ==> B=0
2. 7X+3=9X-7 ==> 2X=10 ==> X=5
3. K-Kx30%=28 ==> K-0.3K=28 ==> 0.7K=28 ==> K=40
4. 50-Y=4(17-Y) ==> 50-Y=68-4Y ==> 3Y=18 ==> Y=6
5. R+Rx20%=36 ==> R+0.2R=36 ==> 1.2R=36 ==> R=30
6. K/5+K/3=16 ==> (3K+5K)/15=16 ==> 8K=240 ==> K=30
7. Px30%+Px50%=24 ==> 0.3P+0.5P=24 ==> 0.8P=24 ==> P=30
8. P/3-P/5=16 ==> (5P-3P)/15=16 ==> 2P=240 ==> P=120

1. 5(2B+3)=15
2B+3=3
2B=0
B=0

2. 7X+3=9X-7
9X-2X=3+7
7X=10
X=10/7


3. K-Kx30%=28
K(1-30%)=28
K=28/70%
K=40


4. 50-y=4(17-Y)
50-y=68-4y
4y-y=68-50
3y=18
y=6


5. R+Rx20%=36
R(1+20%)=36
R=36/(120%)
=36/ (120/100)
=36/1.2
=30

6. K/5+K/3=16
(3K+5K)/15=16
8K=240
K=30


7. Px30%+Px50%=24
P(30%+50%)=24
P(80%)=24
p(80/100)=24
0.8P=24
P=30


8. P/3-P/5=16
(5P-3P)/15=16
2P=240
P=120

2008-03-30 00:19:41 補充：
第二題打錯左,

2. 7X+3=9X-7
9X-7X=3+7
2X=10
X=5