time and distance problem
I would be grateful if you can help me to solve the the below questions
Jackiís mum leaves home at 12.35pm every day and arrives 25 minutes later at his school to pick him up. She always cycles at the same speed along the same route. One day Jacki was dismissed early at 12.30pm, so he started walking home at 6km/h, hoping to meet her along the way. He met her at x and got onto her bicycle. They reached home 15 minutes earlier than before. How far did Jacki walked before his mum picked him up?