Who is b ?

Since the ratio $(b+5):(b - 3)$ is the same as the ratio $2:1$ we can get the equation

$b + 5 = 2(b - 3)$

Expand it to get

$b + 5 = 2b - 6$

Re-arranging it gives us

$b = 2b - 11 \Rightarrow b - 11 = 0 \Rightarrow b = 11$

So the answer is $11$

simply cross multiply to get (b+5)=2b-6.........b=11

If we cross multiply the L.H.S. and the R.H.S., we get- 1(b+5)=2(b-3) =b+5=2b-6 Then after Transposing- =5+6=2b-b =11=b. Simple. :-)

$\begin{aligned} (b + 5) : (b - 3) = 2 : 1 \\ So, \dfrac{b + 5}{b - 3} = 2 \\ So, b + 5 = 2(b - 3) \\ b + 5 = 2b - 6 \\ \therefore b = \color{#EC7300}{\boxed{11}} \end{aligned}$

$\begin{aligned} \dfrac{b + 5}{b + 3} & = \dfrac{2}{1}\\ \\ b + 5 & = 2b + 6\\ b & = \color{#69047E}{\boxed{11}} \end{aligned}$

2(b-3)=b+5 2b=b+11 b=11

the difference btw b+5 and b-3 is 8

b+5 =16, b-3=8

b=11

(b+5):(b-3)=2:1

=>(b+5)/(b-3)=2/1

=>(b+5)=2(b-3)

=>b+5=2b-6

=>6+5=2b-b

=>11=b

Therefore b is 11