Ethan bought a bag of marbles. After giving 1/5 of his marbles to Jacob and 105 marbles to Adam, he had 1/3 of the marbles left. How many marbles did Ethan buy?

Ethans marbles

; x-1/5x-105=1/3x

:x-3/15x-105=5/15x

:12/15x-105=5/15x

:7/15x=105

:1/15x=15

:x = 225