Question

12x + 14x + 4,2 = 12

Answer 1

12x + 14x + 4,2 = 12
(12+14)x = 12 - 4,2
26x = 7,8 = 78/10
$x = frac{78}{10cdot26}=frac{13cdot6}{10cdot13cdot2}=frac{3}{10}=0.3$