A plumber charges a fixed call-out fee plus a fixed hourly rate for the time spent on a job.
A job lasting 2 hours costs £115.
A job lasting 5 hours costs £250.
The plumber's charge, £CCC, for a job lasting t t\,t hours is modelled by a straight line.
Find an equation for C C\,C in terms of ttt.
Interpret the gradient and the vertical intercept of your model in the context of the question.
8 exam-style questions on AQA A Level Maths 1.6.1 Equation of a straight line. Each one has a worked solution and a mark scheme showing where the marks go.