I'm sure it is easy but I just cant get my head around it...

Police car chasing an offender. At point A police car is travelling 90mph and offender is 300 meters ahead. At point B offender is 800 meters ahead.

Distance between A and B is 0.6 Miles.

Speed of police vehicle is constant, 90mph.

What is the minimum speed of the offender to increase the gap by 500 meters?

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