tolong jawab,pake cara ya

jawaban yang C sama D salah pada langkah terakhir
C . 7-15/12 = -8/12 = -2/3
D . 15-32/40 = - 17/40

maaf ya klo salah

a.) 3/5 + 1/4 = 12/20 + 5/20 = 17/30
b.) 5/8 + 2/5 = 25/40 + 16/40 = 41/40 = 1 1/40
c.) 7/12 - 5/4 = 7/12 - 15/12 = (-8)/12 = (-)8/12
d.) 3/8 - 4/5 = 15/40 - 36/40 = (-21)/40 = (-)21/40

maaf kalo salah