Respuesta :

Associative Property of Addition
(1+10) + 18 = 1 + (10 + 18) 
       11 + 18 = 1 + 28
               29 = 29

(1 + 10) + 18 = 11 + 18 = 29 and

1 + (10 + 18) = 1 + 28 = 29