The average number of playing cards Julian and Japheth had was 448. The average number of playing cards Julian and Cole had was 224. If the ratio of Japheth's playing cards to Cole's playing cards was 9 : 2, find the number of playing cards Julian had.
Total number of cards that Julian and Japheth had
= 2 x 448
= 896

Total number of cards that Julian and Cole had
= 2 x 224
= 448

Number of playing cards Japheth had = 9 u
Number of playing cards Cole had = 2 u

Julian's cards + 9 u = 896 --- (1)
Julian's cards + 2 u = 448 --- (2)

(1) - (2)
9 u - 2 u = 896 - 448
7 u = 448
1 u = 448 ÷ 7 = 64

Number of playing cards that Cole had
= 2 u
= 2 x 64
= 128

Number of playing cards that Julian had
= 448 - 128
= 320

Answer(s): 320