Bet $0 \leq x \leq 1000$ at the first bookie and $1000 - x$ at the second bookie. The goal is to maximize
$$\min \\{ 1.36 x - 1000, 4500 - 5.5 x \\}$$
which is the inverted "V" depicted below
![enter image description here](
The maximum is attained when
$$1.36 x - 1000 = 4500 - 5.5 x$$
The maximum is $\approx 90$, which is attained at $x \approx 802$.
There is no need to use linear programming. However, if you really, _really_ do want to use linear programming, then solve the following linear program in $x$ and $t$
$$\begin{array}{ll} \text{maximize} & t\\\ \text{subject to} & 1.36 x - 1000 \geq t\\\ & 4500 - 5.5 x \geq t\\\ & 0 \leq x \leq 1000\end{array}$$