0.52x [multiplier] 5-4x [unknown] = 0.6 7 / 10 [x + 0.9] = 421.3x + 2.4x3 = 12.4

0.52x [multiplier] 5-4x [unknown] = 0.6 7 / 10 [x + 0.9] = 421.3x + 2.4x3 = 12.4

Here are three questions to simplify
(1) 26-4x = 0.6, that is - 4x = - 0.2, so x = 0.05
(2) 7x + 6.3 = 420, that is 7x = 413.7, so x = 59.1
(3) 1.3x = 12.4-7.2 = 5.2, so x = 4