Answer:
2 metre
Step-by-step explanation:
let the width around the field be x metre
then (16+2x)(10+2x)-16×10=120
160+32x+20x+4x²-160=120
4x²+52x-120=0
or x²+13x-30=0
x²+15x-2x-30=0
x(x+15)-2(x+15)=0
(x+15)(x-2)=0
either x+15=0,
x=-15 (Rejected being negative)
or x-2=0
x=2 metre
