A plumber charges a call-out fee of $90 as well as $2 per minute while working - HSC - SSCE Mathematics Standard - Question 10 - 2020 - Paper 1

To express the amount charged by the plumber, we need to account for both the call-out fee and the working time. The call-out fee is $90.

The plumber charges $2 per minute. Since there are 60 minutes in an hour, if the plumber works for t hours, the total number of minutes worked is:

$ext{Total Minutes} = 60t$

The total charge for the working time is:

$ext{Charge for Working} = 2 imes (60t) = 120t$

Therefore, the total cost (C) can be expressed as:

$C = 90 + 120t$