Question

A plumber charges 15 per service call, plus 50 per hour.

Use C for the cost h for the hour.
( Find the slope and y-intercept, make the slope-intercept equation, y=mx+b, and change the variable to fit the problems.

Answer 1

The equation of the cost is C = 50h + 15

Explanation:

The form of the linear equation is y = m x + b, where

• m is the slope of the line ⇒ rate of change

• b is the y-intercept ⇒ constant value

∵ A plumber charges 15 per service call

→ That means there is a fixed amount of 15

∵ b is the constant amount

∴ b = 15

∵ It charges 50 per hour

→ That means, the rate of change is 50

∵ m is the rate of change

∴ m = 50

∵ C is the cost for h hours

→ Replace y by C and x by h in the form of the linear equation above

∴ C = m h + b

→ Substitute the values of m and b in the equation

∵ C = 50h + 15

∴ The equation of the cost is C = 50h + 15