[tex]x + y + z = 1390\\x = y + 120\\x = z - 250\\\\y + 120 = z - 250\\y = z - 250 - 120 = z - 370\\\\z - 250 + z - 370 + z = 1390\\3z - 620 = 1390\\3z = 1390 + 620 = 2010\\z = \frac{2010}{3} \\z = 670 \ lei\\\\y = 670 - 370 = 300 \ lei\\\\x = 670 - 250 = 420 \ lei\\\\[/tex]