a) 38 + 41 + 117 + 159 + 62
= ( 38 + 62 ) + ( 41 + 159 ) + 117
= 100 + 200 + 117
= 300 + 117
= 417
b) 42 . 53 + 47 . 156 - 47 .114
= 42 . 53 + 47 . ( 156 - 114 )
= 42 . 53 + 47 x 42
= 42 . ( 53 + 47 )
= 42 x 100
= 4 200
a,38 + 41 + 117 + 159 + 62
= 38 + 62 + 41 + 159 +117
= ( 38 + 62 ) + ( 41 + 159 ) + 117
= 100 + 200 + 117
= 300 + 117
= 417
b, 42 x 53 + 47 x 156 - 47 x 114
= 42 x 53 + 47 x ( 156 - 114 )
= 42 x 53 + 47 x 42
= 42 x ( 53 + 47 )
= 42 x 100
= 4200