(125 - 47) . x = 25350
78 . x = 25350
x = 325
3978 : x - 987 : x = 1003978 . 1/x - 987 . 1/x = 100
(3978 - 987) . 1/x = 100
2991 . 1/x = 100
1/x = 100/2991
x = 2991/100
#Đức Lộc#
A) 125 * X - X * 47 = 25350
=> X * (125 - 47) = 25350
=> X * 78 = 25350
=> X = 25350 : 78 = 325
B) 3978 : X - 987 : X = 100
<=> 3978 . 1/X - 987 . 1/X = 100
=> 1/X. (3978-987)=100
=>1/X. 2991=100
=> 1/X=100/2991
=> X=1/100/2991
=> X=2991/100