Please help!! This is kinda physics?? But it’s for my math class

Sara needs to take a taxi to get to the movies the taxi charges $4.00 for the first mile and then $2.75 for each mile after that if the total charge is $20.50 then how far was sara’s taxi ride to the movie

Can some one explain this i got sent this. is this a threat i’m scared

Write two point-slope equations for the line passing through the points (6, 5) and (3, 1)