Question

Avery has a total of $12.50 in her piggy bank at home. Each week she takes out $1.25 to ride the city bus. Write an equation representing the balance, C, in the piggy bank, where w is the number of weeks.
A) C = 1.25w – 12.50
B) C = 1.25w + 12.50
C) C = –1.25w + 12.50
D) C = –1.25w – 12.50

Answer 1

Amount now-bus=ballance
bus=number of weeks times how much taken out each time
12.5=amount now
bus=1.25w


C=12.50-1.25w
or
C=-1.25w+12.5

answer is C

Answer 2

For this case we have a function of the form:

$c (w) = mw + b$

Where,

• b: initial amount
• m: weekly rate of change
• w: number of weeks
• c: total balance

We have then that Avery has a total of $ 12.50 in her piggy bank at home:

$b = 12.50$

Each week she takes out $ 1.25 to ride the city bus:

$m = -1.25$

Substituting values we have:

$c (w) = - 1.25w + 12.50$

Answer:

an equation representing the balance, C, in the piggy bank, where w is the number of weeks is:

$c (w) = - 1.25w + 12.50$

Option C