Answer:
Explanation:
The $50 cleanup fee is a "fixed cost."
The "$30 per-person fee is a "variable cost." That is, it varies with the number of people.
 
"within" means "less than or equal to"
 
Cost = $50 + $30x [where x = number of people]
 
Cost ≤ $4500 ["stay within their budget"]
$50 + $30x ≤ $4500 [substitute for cost]
 $30x ≤ $4450 [subtract $50 from both sides retains sense of inequality]
 x ≤ 148.3333 [divide by +$30 retains sense of inequality]
 
Mark and Heather may invite up to 148 guests.
 [note: to be "≤," always truncate, never round up]
 
Check:
 148 people for $30 each + $50 is $4440+$50 = $4490.
One more person makes it $4520 -- that is too much.
There we go, my bad