Algebras: 7x8

Rule: (5+X) × (5+Y) =
(X+Y)×10 + (5-X)×(5-Y)

The variables X and Y are used
to show a general law for numbers!
Replacing X and Y by an arbitrary number, one get's an equality.

X = 2, Y = 3 in the first example,
X = 2, Y = 3 in the second example