6 )Calculati:

a )46:23 + {78-3- [(15 +7.5):5] - 3. 7);
b) 9-{8 +7.[6 +5-(4+3.(2 + 1))]}:(1+2+3+.
c)1+2·[3+4:15-6:07 -8:09 - 1))]}.​