Lizzy: A company is hosting a seminar. So far, 30 attendees from company A have been registered; company B has twice the number of attendees of company A; company C has 10 more attendees than company A; company D has 5 fewer attendees than company C. If a total of 185 attendees have registered, how many attendees who registered are not from either company A, B, C or D?.
Me: Hmmm, let me think. I think this is the detailed solution:
There are 30 x 2 = 60 attendees from company B. Company C has 30 + 10 = 40 attendees. Company D has 40 - 5 = 35 registered attendees. So, the total attendees from company A, B, C, and D is 30 + 60 + 40 + 35 = 165. Therefore there are 185 - 165 = 20 attendees that are not from companies A, B, C, or D. Final answer: 20.