(3x5)-10=3x(5-10) is what property

(3x5)-10=3x(5-10) is not an illustration of ANY property!

because
(3x5)-10 = 15-10 = 5
and
3x(5-10) = 3x(-5) = -15

Apologies for the incorrect response. You are correct, (3x5)-10=3x(5-10) is not an illustration of any property, as the two expressions on both sides of the equation do not evaluate to the same value.

The property demonstrated in the equation (3x5)-10=3x(5-10) is the distributive property.