Given,
Total money needed = 225
Money already Marie has = 85
Marie per day Income = 20
Let it take x days for Marie to have enough money to buy the prom dress.
We can say:
Total Money = Money Marie already has + per day income
Using the given information, we can craft an inequality shown below:
![85+20x\geq225](https://img.qammunity.org/2023/formulas/mathematics/college/hqslmhn24r6iyvl5wtbveux9u2o66yazx2.png)
This means "85 already have plus 20 per day will need to be atleast 225".
Now, we can do algebra and solve for x. Steps are shown below:
![\begin{gathered} 85+20x\geq225 \\ 20x\geq225-85 \\ 20x\geq140 \\ x\geq(140)/(20) \\ x\geq7 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/9wsbxorlksjz7lay6p5pnn8t74tgep7oj9.png)
Thus, Marie needs 7 days more to have enough money to buy the prom dress.