Answer
$L=380, B=120$
Work Step by Step
Let the length of field = L
Let the width of field = B
1. $L=B+2$
2. $2(L+B) = 1000$
$L+B=500$
Put value of L from the first equation to the second equation.
$B+260+B=500$
$2B=500-260$
$2B=240$
$B=\frac{240}{2}$
$B=120$
Put value of B in the first equation.
$L=120+260$
$=380$