The average number of playing cards George and Glen had was 440. The average number of playing cards George and Daniel had was 230. If the ratio of Glen's playing cards to Daniel's playing cards was 9 : 4, find the number of playing cards George had.
Total number of cards that George and Glen had
= 2 x 440
= 880

Total number of cards that George and Daniel had
= 2 x 230
= 460

Number of playing cards Glen had = 9 u
Number of playing cards Daniel had = 4 u

George's cards + 9 u = 880 --- (1)
George's cards + 4 u = 460 --- (2)

(1) - (2)
9 u - 4 u = 880 - 460
5 u = 420
1 u = 420 ÷ 5 = 84

Number of playing cards that Daniel had
= 4 u
= 4 x 84
= 336

Number of playing cards that George had
= 460 - 336
= 124

Answer(s): 124