If Eliza restocked twice the original number of ornamental rings, the number was 200/2= <<200/2=100>>100 rings.
The total number of ornamental rings in stock is now 200+100 = <<200+100=300>>300 rings.
When she sells 3/4 of the stock, the total number of rings sold is 3/4*300 =<<3/4*300=225>>225 rings.
The remaining stock is 300-225 = <<300-225=75>>75 rings.
When her mother buys 300 more rings, the stock is boosted to 75+300 = <<75+300=375>>375 rings.
She then sells out 150, reducing the stock to 375-150 = 225 rings
#### 225