a) I-24I + 155I - I-26I = |-24| + |55| - |-26| = 24 + 55 - 26 = 79 - 26 = 53.
б) 45 + I-5 I+I8I-I-481 = 45 + |-5| + |8| - |-48| = 45 + 5 + 8 - 48 = 58 - 48 = 10.
Ответ: а) 53; б) 10.