Calculați, folosind factorul comun:
a 13.5+13 21+13.40;
c 49. 135-49-27+49.11;
e 2+4+6+8+10+12;
.
b 437.109-437-54+437 - 203;
d 2011.5+2011.7+2011-49+2011 39;
f13.17+13 25-42-11-2.41.