Ghost clock

At 6:15, a ghost conjured a clock that showed the correct time. At that moment, the hands on the clock began to move at the correct speed but in the opposite direction. The ghost reappeared at 7:30 p.m. What time was the clock showing at this moment?

Result

x = 17:00 h

Step-by-step explanation:

$$\begin{gathered} a=6+15/60=\frac{25}{4}=6.25 \\ b=19+30/60=\frac{39}{2}=19.5 \\ d=b-a=19.5-6.25=\frac{53}{4}=13.25 \\ x=a-d+24=6.25-13.25+24=17 \\ x=17=17:00\text{h} \end{gathered}$$

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