Answer:
200 hats
Explanation:
x = the number of hats sold 
y = the number of dollars of expense or income 
 y = 12.5x {the income is $12.50 times the hats sold} 
y = 5.5x + 1400 {the expense is $5.50 times the hats sold plus $1400 in advertising} 
 To break even means for the income to be equal to the expense. 
 12.5x = 5.5x + 1400 {substituted 12.5x, in for y, into bottom equation, setting income equal to expense} 
7x = 1400 {subtracted 5.5x from each side} 
x = 200 {divided each side by 7} 
 The designer must sell 200 hats to break even