a) 6/5 + 4/3 . 7/8 -13/10 = 6/5 + 7/2 - 13/10 = 12/10 + 35/10 - 13/10 = 47/10 - 13/10 = 34/10 = 17/5

b) -11/12 . 18/25 + -11/12 . 7 / 25 + 11/12 = -11/12 . ( 18/25 + 7/25) + 11/12 = -11/12 + 11/12 = 0

c) 12,89 + 27,11 - 43,65 + (-56,35) = (12,89 + 27,11) + ( (-43,65)  + (-56,35) ) = 40 + (-100) = (-60)

d) \(1\dfrac{13}{15}\) . \(\left(0,5\right)^2\) . 3 + (8/15 - \(1\dfrac{19}{60}\)) : \(1\dfrac{23}{24}\)= 28/15 . 0,25 . 3 + (32/60 - 79/60) : 47/24 = 28/15 . 1/4 . 3 + -47/60 . 24/47 = 7/5 + -2/5 = 1