Question

Rezolvati ecuatiile: 1) 5x+20x=20-10x. 2) 2x+90=4x. 3) 3,5x=120-2,5x

Answer 1

$\displaystyle 1).5x+20x=20-10x \\ 5x+20x+10x=20 \\ 35x=20 \\ x= \frac{20}{35} \\ x= \frac{4}{7} \\ 2).2x+90=4x \\ 2x-4x=-90 \\ -2x=-90 \\ x= \frac{-90}{-2} \\ x=45$
$\displaystyle 3).3,5x=120-2,5x \\ 3,5x+2,5x=120 \\ 6x=120 \\ x= \frac{120}{6} \\ x=20$