a = (95 + 123 x 4 ) - (400 +9 x 10 )
a = ( 95 + 492 ) - ( 400 + 90 )
a = 587 - 490
a = 97
b = 30:3:2 x 5 + 35 : 5 + 109 x 4 - 4 x 100
b = 10:2 x 5 + 7 + 436 - 400
b = 5 x 5 + 7 + 436 - 400
b = 25 +7 + 436 - 400
b = 32 + 436 - 400
b = 468 - 400
b = 68
97 + 68 = 165 ( suma )
97 - 68 = 29 ( diferenta )
165 - 29 = 136
R = 136