Last year, Bob's salary was equal to three times Mario's salary this year, meaning Bob was earning 3*$4000 = $<<3*4000=12000>>12000
If Bob's salary increased by 20% this year, he is earning 20/100*$12000= $<<20/100*12000=2400>>2400 more
Bob's total salary this year is $12000+$2400= $<<12000+2400=14400>>14400
#### 14400