The average number of playing cards Luis and Charlie had was 421. The average number of playing cards Luis and Warren had was 229. If the ratio of Charlie's playing cards to Warren's playing cards was 5 : 2, find the number of playing cards Luis had.
Total number of cards that Luis and Charlie had
= 2 x 421
= 842

Total number of cards that Luis and Warren had
= 2 x 229
= 458

Number of playing cards Charlie had = 5 u
Number of playing cards Warren had = 2 u

Luis's cards + 5 u = 842 --- (1)
Luis's cards + 2 u = 458 --- (2)

(1) - (2)
5 u - 2 u = 842 - 458
3 u = 384
1 u = 384 ÷ 3 = 128

Number of playing cards that Warren had
= 2 u
= 2 x 128
= 256

Number of playing cards that Luis had
= 458 - 256
= 202

Answer(s): 202