Alex has x dollars per week available for lunch. She spends $3 on lunch every weekday. Write an algebraic expression to represent how much money she has left over at the end of the week.

The money Alex has left over at the end of the week is (x - $15).

Step-by-step explanation:

The total lunch allowance of a week = $x

The money spent on lunch every weekday = $3

Number of weekdays in a week = 5 days

Now, the total money spend in 5 weekdays

= 5 x (Money spend in 1 weekday) = 5 ($3) = $15

So, in a week she spends $15 in a week.

Total amount Left = Total Money - Money Spent = x - $15

Hence, the money Alex has left over at the end of the week is (x - $15).