Answer:
Assuming you mean width not breadth (What is that)
The width would be: 35m
Explanation:
Now its pretty staight forward
We know that the length is 42m
And the permineter is 154m
We know that the perimeter is the 2 widths and 2 lengths all added up to each other (basically very side added up)
An eaution could be used like, 2w+2l=154
We know length is 42 so
2w+2*42=154
Now just solve for W
2*42=84
2w+84=154
154-84= 70
70=2w
70/2=35
w=35