smoke detector replacement

[mikey12]

Hi all had a customer ask me to look at replacing 2 smoke detectors in house(as been told many times a job is a job) but not sure what to charge as its only replace like for like as far as im aware having a look soon thanks

 

[leeweimaraner]

these are mains i take it i would charge 75 pounds labour this job shouldnt take more than 2 hours 1 hour if your fast dont forget to take into account distance for fuel?