Question

A local plumber charges a house call fee of $25 plus $25 per hour for repair work. How many hours did he work on your sink if your bill comes to $62.50?

Answer 1

Answer:

1 hour and 30 minutes (1.5 hours)

Step-by-step explanation:

$25 per hour is our slope and $25 call fee is our y-intercept.

We can write a linear function in slope-intercept form like this:

$y=mx+b$

Where m is your slope, y is the total cost, x is the hours worked b is your y-intercept.  Therefore using the information above we obtain:

$y=25x+25$

Since the bill comes out to be $62.50 that means that y=62.50 by substituting that value we have to solve for x since x is the amount of hours worked we obtain:

$62.50=25x+25\\\\62.50-25=25x+25-25\\\\37.50=25x\\\\\frac{37.50}{25} = \frac{25x}{25}\\\\1.5=x$

Since x = 1.5 this means that the plumber worked for one and a half hours or 1 hour and 30 minutes.