[tex]a \times (b + 2) = 400.[/tex]
[tex]a = 300 \div b[/tex]
[tex]300 \div b \times (b + 2) = 400 = > 300 \div b \times (b + 2) = 400. \: b \: diferit \: de \: 0. = > \frac{300}{b} \times (b + 2) = 400 = > \frac{300b + 600}{b} = 400 = > 300b + 600 = 400b = >300b - 400b = - 600 = > - 100b = - 600 = > b =6 [/tex]