Question

Choy has $25 in his lunch account at school. He spends $3 each day to eat in the cafeteria, What is Choy's lunch account balance after two weeks of buying his lunch in the cafeteria?

Answer 1

First of all, we need to write a function or equation that describes the behavior of Choy's lunch account at school.

if x will be the numbers of days, y will be the amount of money in his account, then=

$y(x)=25-3x$

Now, after two weeks = 5*2 = 10 days, we need to find y(10) replacing x= 10 in the previous equation, like this:

$\begin{gathered} y(x)=25-3x \\ y(14)=25-3(10) \\ y(14)=25-30 \\ y(14)=-5 \end{gathered}$

Finally, the balance on his account is a debt of 5 dollars.