Question

What is the initial value and rate of change if

Gandalf has 400 quibbles in his account, and he spends 30 quibbles each week

Answer 1

Rate of change = -30

Initial value = 400

Explanation:

Write the equation of the linear function representing this situation. Let

x = number of weeks Gandalf is spending money

y = amount of quibbles left in his account.

Gandalf has 400 quibbles in his account. This means,
`b=400` is the initial value of quibbles Gandalf had in his account

He spends 30 quibbles each week, this means, that he spends 30x quibbles in x weeks and the amount left in his account is

`y=400-30x`

Therefore, the slope is
`-30` and this is the rate of change (negative because the amount of money in his account decreases each week)