Answer:
20m is the length of the other 2 sides
Explanation:
we know that a rectangle has 4 sides and 2 pairs, we know the perimeter is 100m, and a side is 30m its missing its other pair which is 30m so in total its 60m now you subtract that from 100 to get 40 which is the sum of the other pair, so you divide it by 2 to get 20m