F.1 Maths

A + B = 180 , B + C =220, A + C = 200

A + B = 180
+B + C = 220
+C + A = 200
---------------------
(A+B+C)+(A+B+C)=180+220+200
2(A+B+C)=600
A+B+C=300

A+B+C=300
- B+C=220
------------------
A =80

A+B=180
-A =18
-------------
B =100

A+C=200
-A =80
-------------
C =120

A=180
B=100
C=120

(A+B)+(B+C)+(A+C)=2A+2B+2C
180+220+200=2(A+B+C)
600/2=A+B+C
A+B+C=300

300-A+B=C
300-180=C
C=120

300-B+C=A
300-220=A
A=80

300-A+C=B
300-200=B
B=100

2007-04-11 15:16:48 補充：
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A + B = 180.....................(1)

B + C = 220.....................(2)

A + C = 200.....................(3)

(1),
A + B = 180
B = 180 - A

Subst. B = 180 - A into (2)
180 - A + C = 220...................(4)

(4) - (3),
180 - A + C - (A + C) = 220 - 200
180 - A + C - A - C = 20
180 - 2A = 20
180 = 20 + 2A
160 = 2A
A = 80

Subst. A = 80 into (1)
80 + B = 180
B = 100

Subst. A = 80 into (3)
80 + C = 200
C = 120

Therefore,,A=80,B=100,C=120

先找出其中一個化數 : A=180-B

180-B+ C = 200

180-B+C-180=200 - 180
-B+C=20
-B-(-B)+C =20-(-B)
C= 20+B

THEN
B+C=220
B+20+B=220
2B+20=220
B=100
THEN
C=20+B
C=120

IF A+C=200
A+120=200
A=80


A+C=200

A=80
B=100
C=120

A + B = 180 --------------------- 1
B + C = 220 --------------------- 2
A + C = 200 --------------------- 3

1 :
A + B = 180
i.e. B = 180 - A

subs into 2 :
we get 180 - A + C = 220
i.e. C = 220 -180 + A
C = 40 + A

subs into 3 :
we get A + 40 + A = 200
i.e. 2A = 200 - 40
2A = 160
A = 80

subs into 1 :
80 + B = 180
B = 100

subs into 2 :
100 + C = 220
C = 120

(A + C)-(A + B )=20
∴C-B=20

假設B:100
C:120

A+100(B)=180
∴A:80

B+120(C)=200
∴A:80

∴A:80
B:100
C:120



P.S.我是P.6學生

A=80,C=120
因為C-A=40,
所以A+(A+40)=200
2A=160
A=80
C=A+40
所以C=120

Question:A + B = 180 , B + C =220, A + C = 200


Answer:

A=80

B=100



C=120

2007-04-10 18:46:14 補充：
A B=180(80) (100)=180B C=220(100) (120)=220A C=200(80) (120)=200.

2007-04-10 18:46:25 補充：
A B=180(80) (100)=180B C=220(100) (120)=220A C=200(80) (120)=200.

2007-04-10 18:51:03 補充：
A=80,C=120BecauseA=40,ThereforeA (A 40)=2002A=160A=80C=A 40所以C=120 BecauseA B=180(80) (?)=180180-80=100Therefore B=100