Lets say the length is x and the width is y.
The perimeter is calculated by using 2x +2y=120 and we know that the difference of x and twice y is 24, x-2y=24 so, lets use this and solve for x.
Add 2y to both sides and get x=2y+24. Now we can use substitution into the perimeter equation because we know what x equals.
2(2y+24) +2y=120 Now solve for Y.
4y+48+2y=120
6y+48=120
6y=72
y=12 Your width is 12feet. Now use twelve in your perimeter equation and solve for X
2x+2y=120 so,
2x +2(12)=120
2x+24=120 subtract 24 from both sides
2x=96 divide by 2
x=48 your length is 48 meters.