$10 + \dfrac{x}{12} + \theta = 15$
$\theta = 5 - \dfrac{x}{12}$
$x = 15 + \theta$
$x = 15 + \left( 5 - \dfrac{x}{12} \right)$
$x = 20 - \dfrac{x}{12}$
$\dfrac{13x}{12} = 20$
$x = 18.46 \, \text{ min}$
$x = 18 \text{ min and } 27.6 \text{ sec}$
$\text{Time} = 2:18:27.6$ answer - A
Preferred Solution
$\theta = \theta$
$x - 15 = 5 - \dfrac{x}{12}$
$x = 18.46 \, \text{ min}$