Tìm x, biết:

tìm x, biết:
a) 30 . ( x - 60 ) = 30
b) (3x - 25) . 7=42
c) ( x -2) . (x-5) = 0
d) x . (x - 1) = 0
e) 105 - [( 2x + 7) - 13] = 25
f) 5 . (x - 3) -3 . x = 5
l) 1 + 5 + 9 + 13 + 17 +...+ x = 4950
h) 250 : x - 10 = 50 : 5 . 2 - 5
k) (x + 1) + (x + 2) +...+ (x + 19) = 204