Jawabanmu

2014-03-06T22:45:50+07:00
Sn=n/2 (U1+Un)
S33=33/2 (7+U33)
819=33/2 (7+U33)
U33=42,636
2014-03-06T22:46:45+07:00
33x7=231 atau gak salah 33 +7= 40 maafvkalo salhvyahh