Hey.
[tex]\dfrac{3}{8} = \dfrac{9}{b} +10 \\ \\ \implies \dfrac{3}{8} = \dfrac{9+10b}{b} \\ \\ \implies \dfrac{3}{8} \times b = 9+10b \\ \\ \implies b = 9+10b \times \dfrac{8}{3} \\ \\ \implies b= \dfrac{72+80b}{3} \\ \\ \implies 3b = 72 + 80b \\ \\ \implies 3b-80b = 72 \\ \\ \implies -72b = 72 \\ \\ \implies b = -\dfrac{\cancel{72}}{\cancel{72}} \implies \boxed{b = -1 }[/tex]
Thanks.
