The height of the above-water part of the iceberg is 30 m, this is an eighth of its entire height.

The height of the above-water part of the iceberg is 30 m, this is an eighth of its entire height. How deep does the iceberg go under water?

According to the condition, in total we have 8 identical parts of the iceberg, 30 meters each. One of them (1/8) is above water, and 7 (7/8) parts are under water.
Let’s find to what depth the iceberg goes under the water.
30 * 7 = 210 m
Answer: the iceberg goes under water to a depth of 210 meters.