Question

Samantha started with $25 in her account. she saves $7 per week. Australia has no money in his account, but adds $15 per week. for how many weeks will Australia have more money in his account than Samantha

Answer 1

In this problem we can made a function to calculate the total amount for Samantha (S) and total amound of Australia (A) fon any time:

`\begin{gathered} S=25+7t \\ A=0+15t \end{gathered}`

when t is the number of weeks. if we made equal the ecuation we will have the time when they would have the same amound:

`\begin{gathered} S=A \\ 25+7t=15t \end{gathered}`

and we solve for t

`\begin{gathered} 25=15t-7t \\ 25=8t \\ (25)/(8)=t \\ 3.125=t \end{gathered}`

This means that in the next full number Australia will have more money than Samantha, so in 4 weeks this is going to happen.