Anyone explain this math problem please

The sum of the length and the width of a proposed feed lot is 1260 ft. Find the length and width if their ratio must be 5:2.

l:w = 5:2


l+w = 1260
5x+2x = 1260
7x=1260
x=180

l = 5x = 5*180 = 900
p= 2x = 2*180 = 360

Anyone explain this math problem please?
The sum of the length and the width of a proposed feed lot is 1260 ft. Find the length and width if their ratio must be 5:2.
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L + W = 1260

If their ratio is 5:2, then the length is 5/(5+2) x 1260,

or 900 ft; the width is 5/(5+2) x 1260, or 360 ft.