Answer:
15m
Explanation:
Let w be the width, l the length and p the perimeter.
We know, by definition, that p = 2w + 2l. We also know that p = 80m and l = 25m.
So we can re-write the perimeter formula as:
80 = 2w + 50
2w = 30
w = 15m
So we now know that the width is 15m.