Question

Aflati x:
x - x\3 - 30\100 (x - x\3) = 420
(x-1)\3 + (1-2x)\2 = 5\6
x - x\3 - 50\100 (x - x\3) =60

Answer 1

notez x-x/3=a ⇒ a-3a/10=420⇒ 10a/10-3a/10=420⇒ 7a/10=420⇒ 7a=4200⇒ 
a=4200:7⇒ a= 600 ⇒ 3x/3-x/3=600⇒ 2x/3=600⇒ 2x=1800⇒ x=900

2(x-1)/6 + 3(1-2x)/6=5/6
2x-2+3-6x / 6 =5/6
2x-2+3-6x=5
-4x+1=5
-4x=5-1
-4x=4
-x=4:4
-x=1
x=-1

notez x-x/3=a
100a/100-50a/100=60
50a/100=60
a/2=60
a=60*2
a=1200
3x/3-x/3=1200
2x/3=1200
2x=1200*3
2x=3600
x=3600:2
x=1800

Answer 2

x-x/3-(30÷100)(x-x/3)=420        x-x/3=(3x-x)/3=2x/3
x-x/3 -(3/10 )x2x/3=x-x/3 -x/5 =420 numitorul comun e 15⇒7x/15=420⇒x=90
b)numitor comun 6  ⇒2(x-1)+3(1-2x)=5      2x-2 +3-6x=5⇒ -4x=2⇒x=2/4=-1/2
c)x-x/3 -1/2(x-x/3)=60      x-x/3=2x/3       ⇒x-x/3  -(1/2)2x/3=60  numitorul comune 3   3x-x-x=180  ⇒x=180