What is y? (look at the picture I attached, thank you!)

Step-by-step explanation:

or, 3(2y-4) = 1(y+7)

or, 6y-12 = y +7

or, 6y-y = 7+12

or, 5y = 19

or, y = 19/5

(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