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Ajutor ->. 3,5x =120-2,5x. 2x+90=4x

Răspuns :

[tex]\displaystyle a).3,5x=120-2,5x \\ 3,5x+2,5x=120 \\ 6x=120 \\ x= \frac{120}{6} \\ \\ x=20 \\ b).2x+90=4x \\ 2x-4x=-90 \\ -2x=-90 \\ x= \frac{-90}{-2} \\ x=45 [/tex]