19 x 64 + 76 x 34

= 19 x 64 + 19 x 4 x 34

= 19 x 64 + 19 x 136

= 19 x (64 + 136)

= 19 x 200

= 3800
 

a. (2+4+6+...+100) x (36 x 333-108 x 111)

= (2+4+6+...+100) x (36 x 3 x 111-108 x 111)

= (2+4+6+...+100) x (108 x 111-108 x 111)

= (2+4+6+...+100) x 0

= 0