Explanation
Step 1
let x represents the numbers of days you can stay at the beach
then,
You estimate that it will cost $160 a day for food, entertainment and hotel, plus $230 round trip airfare.
so
[tex]\text{total}=230+160x[/tex]but, you have only $1200, so the total needs to be smaller or equal than 1200
[tex]230+160x\leq1200\rightarrow Inequality[/tex]Step 2
solve the inequality
[tex]\begin{gathered} 230+160x\leq1200\rightarrow Inequality \\ subtract\text{ 230 in both sides} \\ 230+160x-230\leq1200-230 \\ 160x\leq970 \\ \text{divide both sides by 160} \\ \frac{160x}{160}\leq\frac{970}{160} \\ x\leq6.0625 \\ \text{rounded} \\ x\leq6 \end{gathered}[/tex]it means you can stay maximum 6 days
I hope this helps you