**given:**

length=32m

area of field=768m

breadth=?

l*b=area

32m*b=768m

b=768/32

** =24**

As we now know the length and breadth, we can easily find the perimeter,

Now,

perimeter=2(l+b)

=2(32m+24m)

=2*56

**=112m**

Cost of fencing per metre=Rs.20

Cost of fencing for 112m=112m*Rs20

**=Rs.2240**