Patti is using mental math to evaluate the expression . she recognizes that the expression will be easier to simplify if she can combine 70 and 30 before she works with the other numbers. how do the properties of operations allow patti to take that approach? she can use the associative property to rewrite the expression as . she can use the associative property to rewrite the expression as . she can use the commutative property to rewrite the expression as . she can use the commutative property to rewrite the expression as .