We have the following:
black drone:
[tex]1170-64\cdot n[/tex]
white drone:
[tex]966-52\cdot n[/tex]
now, we must equal the two equations since they tell us that they are at the same height:
[tex]1170-64\cdot n=966-52\cdot n[/tex]
solving for n, n = time in minutes
[tex]\begin{gathered} 64\cdot n-52\cdot n=1170-966 \\ 12\cdot n=204 \\ n=\frac{204}{12} \\ n=17 \end{gathered}[/tex]
therefore, at 17 minutes both drones are the same height
