So here. I don't know how to explain so-
Of means multiply
3/5 *n=30
3/5 5/3 cancels than you do 30 *5/3 =50
The answer is 50 you can check your answer by doing 3/5 *50=150/5 or 30 so it's correct .
Huxsjxjsjxwxbwhudnuwudwudywydbywbhbdwbhdjwndjwbidnjwjdejndunundeuxnennxuenjjxenjxnjrncrnjncndjcnjencjejnjcnjenfuejndjjnenfjnendjwnjdnjwnc