Question

Which situation below would represent a negative rate of change:

John's parents put $40 on his school account for lunch. Each day he pays $3 for
lunch. Let y represent the amount of money John has after x days in his school
account.
Judy is babysitting after school and charges $20 a day. Each day she gets paid, she
puts half of what she earns in a savings account. Let y represent the amount of
money Judy has in her bank account after x days.

Answer 1

Answer: John's situation

Explanation:

Hi, to answer this question we have to write an equation for each situation.

John’s situation:

The amount of money that John has (y) is equal to his school account (40) minus the product of the number of days (x) and the amount he spends per day( 3)

y =40-3x

As days pass by, John has less money (negative rate of change)

Judy's situation

The amount of money that Judy has in her savings account (y) is equal to the product of the number of days (x) and the amount he saves per day (20/2)

y = x (20/2)