Solve the Problem $f ( x ) = 45 x - 30$

Multiple Choice

Solve the problem.
-An electrician charges a fee of $45 plus $30 per hour. Find a linear function f(x) = mx + b whose input is the number of hours worked and whose output is the total cost of the job. Find the Slope-intercept form of the equation.

A) $f ( x ) = 45 x - 30$
B) $f ( x ) = 45 x + 30$
C) $f ( x ) = 30 x - 45$
D) $f ( x ) = 30 x + 45$