W
h
i
c
h
o
f
t
h
e
f
o
l
l
o
w
i
n
g
f
o
r
m
u
l
a
c
a
n
c
a
l
c
u
l
a
t
e
t
h
e
t
o
t
a
l
n
u
m
b
e
r
o
f
a
n
i
m
a
l
s
?
=
4
5
3
+
5
7
2
+
3
8
6
+
9
4
7
+
7
3
5
=
A
1
+
A
2
+
A
3
+
A
4
+
A
5
=
B
3
+
B
4
+
B
5
+
B
6
+
B
7
