Question

$\frac{x+1}{3} = \frac{4,2}{7}$

Answer 1

multesti pe diagonala  produsul mezilor cu prdusul extremilor
7(x+1)=3x4,2
7x+7=12,6
7x=12,6-7=5,6
x=7/5,6=>7/56/10=7x10/56=5/4

Answer 2

12,6=7x+7 rezulta 7x=5,6 rezulta x=0,8