What is the standard form of the equation of the parabola with a directrix at x=7 and a focus at (12,-15)?

Equation of Parabola is $x = \frac{1}{10} \cdot {\left(y + 15\right)}^{2} + 9.5$
Vertex is at mid-point between vertex and directrix. So vertex is at $\left(9.5 , - 15\right)$ The equation of Parabola is $x = a \cdot {\left(y + 15\right)}^{2} + 9.5$ now $a = \frac{1}{4 \cdot d}$ where d is distance between vertex and focus $\therefore a = \frac{1}{4 \cdot 2.5} \mathmr{and} a = \frac{1}{10}$ So Equation of Parabola is $x = \frac{1}{10} \cdot {\left(y + 15\right)}^{2} + 9.5$ graph{x=1/10*(y+15)^2+9.5 [-80, 80, -40, 40]} [Answer]