a . S = 3 + 12 + 45 + 97 + 25 + 87 + 163
S = ( 3 + 163 + 45 ) + ( 12 + 87 ) + ( 97 + 25 )
S = 200 + 99 + 122
S = 322 + 99
S = 421
b. S = 200 + 175 + 113 + 37 + 25 + 87 + 163
S = 200 + ( 175 + 25 ) + ( 113 + 87 ) + ( 163 + 37 )
S = 200 + 200 + 200 + 200
S = 800
c. S = 19 + 32 + 58 + 91 + 42 + 81 + 55 + 9 + 100
S = ( 19 + 81 ) + ( 58 + 42 ) + ( 91 + 9 ) + ( 55 + 32 ) + 100
S = 100 + 100 + 100 + 87 + 100
S = 487
SUCCES !!