Answer:
Number of marbles with Williams at the starting = 192
Explanation:
Let total number of marbles with Williams = m
He lost marbles = 25% of the total number
=

=

Remaining marbles with Williams = m -

=

He gave marbles to his brother =
th of the remaining marbles
=

=

Remaining marbles after giving marbles to his brother = 120
Therefore,



m =

m = 192
Number of marbles with Williams at the starting = 192