He had 20 red marbles and took away 3 leaving 20-3 = <<20-3=17>>17 red marbles
He took 4 times as many blue marbles as red marbles which is 4*3 = <<4*3=12>>12 blue marbles
He took 12 blue marbles from 30 leaving 30-12 = 18 blue marbles
He now has 17+18 = <<17+18=35>>35 marbles left
#### 35