A landscaper buried a waterline around a rectangular long to serve as supply supply line for a sprinkler system. The length of the lawn is five times it’s width. If 420 feet of pipe was used to do the job, what is the length and the width of the lawn?

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18

21

jk it's 20

step-by-step explanation: