Twelve apples cost $2. how much will 50 apples cost?

2 over 12 is equal to x over 50.  

Then you use cross products (multiply 2 by 50 and multiply 12 by x)  

You end up with 12x=100.  

Divide both sides by 12 and you end up with $8.33.

(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

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