Answer:
t = 4 h
Step-by-step explanation:
Painter A initial fee 40 $ and each hour charge 45 $
Painter B initial fee 100 $ and each hour charge 30 $
The equations for painters are straight lines.
The initial fee is the intercept of the line with the y-axis ( painters receive 40 and 100 $ respectively and they have done nothing.
The equation for a straight line is:
y = m*x + b where m is the slope and b the intercept with the y-axis
Then
Painter A when x = 0 y = b = 40
And each hour of work cost 45 $ then f x = t in hours
The equation for Painter A is y = 45*t + 40
Similarly, the equation for Painter B is
y = 30*t + 100
We have a two equations system, the solution will indicate when the two painters will charge the same amount of money
y = 45*t + 40 (1)
y = 30*t + 100 (2)
Equation 1 - equation 2
0 = 15*t - 60
15*t = 60
t = 60/15
t = 4 h
