If Clara doubles a number and then adds 3, the result is 23. The original number is
(A) 13 (B) 10 (C) 49 (D) 17 (E) 20
Want a route through all this instead of an archive? The track
puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.
Source: CEMC, University of Waterloo,
licensed CC-BY-NC-4.0.
Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.