Question

Tìm x :

X*20%+X*50%=70

X*12+X*88=90000

12+24+36+x+x+x+x=108

x+x+x+x+x+x+x+x+x+123=204

Answer 1

a) x * 20 % + x *50% = 70

=> x * ( 20% +50% ) = 70

=>x * 70 % = 70

=> x = 70 : 70 % = 100

b) x*12 + x * 88 = 90 000

=> X *(12+88) = 90 000

=> x * 100 = 90 000

=> x = 90 000 : 100 = 900

c) 12+24+36+x+x+x+x = 108

=> 72 + x*4 = 108

=> x*4 = 108 - 72 = 36

=>x = 36 : 4 = 9

d) x+x+x+x+x+x+x+x+x +123 = 204 

=> 9*x +123 = 204

=> 9*x = 204 - 123 = 81

=> x = 81 : 9 = 9 

Bài này dài thật ^^