Will give a

which ordered pair (c, d) is a solution to the given system of linear equations?

-c+2d=13
-9c-4d=-5

(–1, 6)
(–1, 7)
(6, –1)
(7, 10)

(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