First Round, January 2019

Every day, Maurits bikes to school. He can choose between two different routes. Route $B$ is $1.5$ km longer than route $A$. However, because he encounters fewer traffic lights, his average speed along route $B$ is $2$ km/h higher than along route $A$. This makes that travelling along the two routes takes exactly the same amount of time. How long does it take for Maurits to bike to school?