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a)5+20x=20-10x;
b)2x+90=4x;
c)3,5x=120-2,5x


Răspuns :

a)5+20x=20-10x
20x+10x=20-5
30x=15
x=15:30=0,5
b)2x+90=4x
90=4x-2x
90=2x
x=90:2=45
c)3,5x=120-2,5x
3,5x+2,5x=120
6x=120
x=120:6=20
[tex]a).5+20x=20-10x \\ 20x+10x=20-5 \\ 30x=15 \\ x= \frac{15}{30} \\ b).2x+90=4x \\ 2x-4x=-90 \\ -2x=-90 \\ x= \frac{-90}{-2} \\ x=45 \\ c).3,5x=120-2,5x \\ 3,5x+2,5x=120 \\ 6x=120 \\ x= \frac{120}{6} \\ x=20[/tex]