the cost of cultivating a rectangular field at ra 35 per square metre is rs 71400. if the width of the field is 40 m.find its length.also cost of the fencing the field at rs 50 per metre

Total cost of cultivating the rectangular field = Rs.71400
Rate = 35 per sqm.
So area of rectangular field = $\frac{71400}{35} = 240 m^2$
Suppose the length of field is l .
And width of field = 40 m
So, area of field = $40\times l = 240$ sq.m.
$\Rightarrow l = \frac{240}{40} = 6 \mathrm{m}$
So perimeter of rectangular field = $2\left(40+6\right) = 2\times 46 = 92 \mathrm{m}$
So, Cost of fencing per meter = Rs.50
Therefore, total cost of fencing 92 m = $92\times 50$ = Rs.4600