a
a
=
a
2
5
5
=
1
2
5
2
5
5
=
1
1
z
5
=
0
1
z
1
z
z
2
z
3
z
4
=
0
1
z
z
2
z
3
z
4
=
0
1
z
z
2
1
z
1
z
2
=
0
1
1
1
z
2
z
1
z
=
1
z
z
2
1
z
1
z
2
solve
1
x
x
2
x
1
5
2
z
1
z
1
5
2
z
1
z
=
0
2
2
z
2
z
1
5
=
0
a)
solve
2
2
z
2
z
1
5
z
z
=
1
5
2
5
5
4
z
=
1
5
2
5
5
4
2
2
z
2
z
1
5
=
0
b)
solve
2
2
z
2
z
1
5
z
z
=
1
5
2
5
5
4
z
=
1
5
2
5
5
4
2
5
2
5
=
z
=
1
5
2
5
5
4
=
1
5
2
5
5
4
2
5
=
1
5
4
2
a
=
2
a
2
1
subst
2
a
2
1
a
5
2
5
2
1
=
1
5
4
solve
2
5
2
1
5
4
1
5
5
=
2
3
5
4
0.8090169943749475
=
0.8090169943749475