A magician has a top hat with 20 red marbles and a top hat with 30 blue marbles. If he takes away 3 red marbles and four times as many blue marbles as red marbles (without looking), how many marbles in total does he have left?
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