Round to the nearest ten hundred and thousand 8,441

Customers at an ice-cream shop took a survey .the results showed that 144 customers rated the shop as being "very satisfactory ."this number represented 45%of the total nunber of customers who took the survey

With these: 18/36 = 1/? missing number change 1 5/8 to improper fraction. change 19/5 to a mixed number.

How do you use the elimination method for this question? explain, because i really want to understand!