Math a scientist uses a submarine to study ocean life she begins at sea keve which is and elevation of 0 ft she travels straight down for 90 seconds at my a speed of 3.5 ft per second she travles directly up for 30 seconds at a speed if 2.2

Think of it like this: the amount of distance traveled is the product of the time taken to travel, and the amount traveled after a certain amount of time. Basically multiply 90/30 and 3.5/2.2. 

So, she travels downwards 315 feet from 0 feet, then ascends upwards 66 feet. That only leaves finding the difference between the two numbers to determine where she is after 120 seconds of time (the sum of the amounts of time it took to go down and back up a bit). 

315 - 66 = 249. 

Therefore, she is now 249 feet below the surface after 120 seconds/2 minutes.