Tìm x

Bài 2: Tìm x, biết:
a/ (x+2) + (x+4) + (x+6) +...+(x+100) = 2650;
b/(x+3) + (x+5) + (x+7)+...+(x+97) = 2496;
c/x.2 + x .5 = 14;
e/ x:13/2 +
+x. = 1999;
g/11.(x-6) = 4.x + 11;
k/ (5.x+7): x + 20 = 26;
Bài 3: Cha
d/x.9 + x = 20;
f/11.(x+2) = 5. x+40;
h/ (3.x-4): x + 10 = 12;
m/x.1999 - x = 1999.1997 + 1999.