The arrangements for 'BOBLE': 5!/2!= 120/2 =60.
The arrangements for 'VOWELS': 6!=720.
Total arrangements treating each word as a unit: 2×60×720=86400.
Set up the equation: 86400 =5!×4!×k(k+1)(k2+1)(log10(k3+2)).
Solve for k by substituting values and simplifying the equation.
We get k = 4