1) 18,25 - (7,5 -15,5) + 4 = 18,25 - 8 + 4 = 10,29
2) 18,4 - ( 27-17,75+8,5) = 18,4- (9,25+8,5) = 18,4-17,75 = 0,65
3) (8,125- 0,5)- ( 13,25 - 3,5)+ (11,875 - 23,6) = 7,625 - 9,75 + (-11,725) = -2,125 + (-11,725)= -13,85
4) ( 1,7-4,6-0,13+6) - ( 7-50,91+0,25) = 2,97 - (-43,66) = -40,69