the easiest way is to take the motorbike, collect the 1st 2 bombs the arrow points to, then go back to were you got the bike from (ya know the parking lot, so you'd better remember the way, just look for the barriers) and get a fresh bike, then collect the next 2 bombs, then get a fresh bike, then get the final bomb and get back to the parking lot, and thats that! don't worry about beating Carlito down there!