Tìm x, biết:

Bài 2.4. Tìm x, biết:
x+5 x+6
+
2005 2004
a)
b)
c)
d)
x+1
65
-+
x + 3
63
x+7
2003
x+5 x+7
+
61 59
+
x+27 x+17 x+15
33
43
45
x+29
31
x+6 x+8 x+10 x+12
+
1999 1997 1995 1993
=
+
1909 x 1907-x 1905-x
e)
+
91
93
95
+
+
1903-x
97
+4=0