Given:
Profit = 372.60 + 17.2(advertising dollars)
Advertising dollars = 1,020
profit = 17,500
17,500 + residual value = 372.60 + 17.2(1,020)
17,500 + residual value = 372.60 + 17,544
17,500 + residual value = 17,916.60
residual value = 17,916.60 - 17,500
residual value = 416.60
residual value is 416.60 or 417 rounded off to the nearest integer
You can solve this with next proportion =>
3 : 5 = 4 : x => 3x= 5*4 => 3x = 20 => x=20/3 = 6 (2/3)
The correct answer is x= 6 (2/3)
Good luck!!!