Question

[(3×x-261):3+159]×2=390

Answer 1

[(3×x-261):3+159]×2=390
[(3×X-261:3+159] = 390:2
(3×X-261):3+159 = 195
(3×X-261):3 = 195-159
(3×X -261) :3 = 36
3×X - 261 = 36×3
3×X-261 = 108
3×X = 108+261
3×X = 369
X= 369:3
X = 123

Verificare:

3×123 = 369
369-261 = 108
108:3 = 36
36+159 = 195
195×2 = 390