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.

Answer 1

Since the starting amount is \($12.50\), the amount in her piggy bank in \(\text{week 0}\) is \($12.50\)

Answer 2

Can you guess the amount in her piggy bank during \(\text{week 1}\) ?

Answer 3

11.25

Answer 4

Yes! because she takes out \(1.25\) :
\[\large 12.50-\color{red}{1.25} = 11.25\]

Answer 5

can you guess the amount in her piggy band during \(\text{week 2}\) ?

Answer 6

10

Answer 7

Correct! you must have worked it by subtracting \(1.25\) again :
\[\large 12.50-\color{red}{1.25} -\color{red}{1.25} = 10\]

Answer 8

i know how to subtract. i just need help with how i write the equation. I know that it begins like "C=......"

Answer 9

Notice the pattern ? can you find the amount in her piggy bank during \(\text{week} 8\) ?

Answer 10

you just need to subtract \(\color{red}{1.25}\) for \(8\) times right

Answer 11

so the amount in the bank after \(w\) weeks is given by :
\[C ~~=~~12.50~-~\color{red}{1.25}w\]

Answer 12

Those are my choices

C = 1.25w – 12.50
C = 1.25w + 12.50
C = –1.25w + 12.50
C = –1.25w – 12.50

Answer 13

Would i just move it around????

Answer 14

I thought that it was C=12.50-1.25w but thats not up there.

Answer 15

Yes
\[C ~~=~~12.50~-~\color{red}{1.25}w\]

is same as
\[C ~~=~-~\color{red}{1.25}w~+~12.50\]

Answer 16

ohhhhhhh okay. haha. thats all i really needed to know. Thank you.

Answer 17

yw!