Puzzle problem

Oct 2008
41
0
Hi there!

\(\displaystyle 6*7=30\)
\(\displaystyle 7*5=24\)
\(\displaystyle 4*9=24\)
\(\displaystyle 8*5=?\)

According to the first three relations find \(\displaystyle 8*5=?\).

Thank you.
 
Feb 2007
11,663
4,210
New York, USA
Hi there!

\(\displaystyle 6*7=30\)
\(\displaystyle 7*5=24\)
\(\displaystyle 4*9=24\)
\(\displaystyle 8*5=?\)

According to the first three relations find \(\displaystyle 8*5=?\).

Thank you.
here is the relation: \(\displaystyle a*b = (a - 1)(b - 1)\)

EDIT: well geez, thanks a lot Adarsh. I left the problem unanswered so long, but you decided to answer right before i did :p