please help me to answer this kind of question-_-

a. 6a+18-5a+24
= a+42
c. 27c-18-10-5c
= 22c-28
e. 84-35e-27+21e
= -14e+57
g. -8g+2g²-6g²-3g
= -4g²-11g
i hope this helps