Bob needs his refrigerator fixed. The repairman will charge Bob a flat fee of $40 plus an additional $15 for each hour he needs to work on it. Write an equation to represent Bob's cost to repair his refrigerator. Use y for the total cost and x for hours.

Given:

Fixed fee = $40

Additional fee = $15 per hour

To find:

The equation to represent Bob's cost to repair his refrigerator.

Solution:

Let y be the total cost for x hours.

Additional fee for one hour = $15

Additional fee for x hour = $15x

Total cost = Fixed fee + Additional fee

Therefore, the required equation is .

step-by-step explanation:

5x + 3y = - 4

step-by-step explanation:

the equation of a line in standard form is

ax + by = c ( a is a positive integer and b, c are integers )

express the line first of all in slope- intercept form

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (7, - 3) and (x₂, y₂ ) = (4, - 8)

m = = -

y = - x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (4, - 8 ), then

- 8 = - + c ⇒ c = -

y = - x - ← in slope-intercept form

multiply all terms by 3 to eliminate the fractions

3y = - 5x - 4 ( add 5x to both sides )

5x + 3y = - 4 ← in standard form