Let's say the width is equal to x
We can then say that the length is 2x
We need to add together 2 of both sides;
2x+2x+x+x = 6x
Then we can divide 420 by 6 to get the width:
420/6 = 70ft
Then double it to get the length:
70*2 = 140ft
width = 70ft
length = 140ft
Hope this helps! :)
