A small submarine started its dive at sea level and descended 30 feet per minute. Which integer represents the submarine’s depth after seven minutes?
210 feet
-23 feet
37 feet
-210 feet
The submarine descends 30 feet per minute, so after 7 minutes it will be at a depth of 7*30 = <<7*30=210>>210 feet.
Therefore, the integer that represents the submarine's depth after seven minutes is 210 feet.