Ravi : Peter : Meng

=  2     :    3     :    4

=  4u   :    6u    :   8u    (x 2, preparing the units for Ravi to give away his “quarter”)

(above ratio is before)

After Ravi gives 1/4 to Meng, ratio becomes

= 3u    :    6u   :   9u

— when we compare P and M, M has 9u-6u = 3u more –> 15 cards

Meng has 9u, so multiply by 3 –> 15×3 = 45 cards in the end.