S
≈
8
5
.
8
7
A
B
≈
1
7
.
3
7
B
C
≈
1
4
.
2
0
A
C
≈
1
2
.
2
2
s
≈
2
0
.
2
2
4
3
S
(
2
A
B
+
2
B
C
+
2
A
C
)
/
(
9
2
A
B
×
2
B
C
×
2
A
C
)
≈
2
0
.
2
2