The only triangle with the base being bisected perpendicularly is an isosceles triangle or an equilateral triangle. Therefore,
![KJ = KL](https://img.qammunity.org/2021/formulas/mathematics/high-school/3cf8w6rpd7tfqme0ys2w919eqc07i8tsaw.png)
![KJ = 4x + 9\\KL = 11x - 61\\](https://img.qammunity.org/2021/formulas/mathematics/high-school/fo228izsf73t80eixejagmyh6k59bp2ye6.png)
Since the sides are equal, we can equate the expressions to get the equation:
![4x + 9 = 11x - 61\\11x - 4x = 70\\x = 10](https://img.qammunity.org/2021/formulas/mathematics/high-school/mliaasfjt9qn9kkxd2wx8lq9by9ys36uq9.png)
is equal to
.
Plug that in
and you get
which is
. So, Option B is correct :D