Answer:
smallest number of signs that he sell is 14
Step-by-step explanation:
Given data 
charges = x dollars
sells = 44−x signs per week
income = $420
to find out 
smallest number of signs
solution
we consider he sell small x number of signs
so 
we can say here 
income = price × quantity
so
420 = x (44-x) 
420 = 44x - x²
x² - 44x + 420 = 0
x=14 or x=30
here small no is 14 
so smallest number of signs that he sell is 14