what is the rate of change in the price of the washer-and-dryers between Week1 and Week5?

Answer:
-$11.45/week
Step-by-step explanation:
The rate of change in washer price would be determined by the formula below:
Rate of Change = (Price in Week 5 - Price in Week 1)/(5th Week - 1st Week)
So, the Final Price (Week 5) = $694.99
Initial Price (week 1) = $740.79
From Week 1 to Week 5 is 4 weeks passed.
Putting into formula:
Rate of Change = (694.99 - 740.79) /4 = -$11.45/week