Answer :

45 times 2/3= 30
30x 1/5=6

36 posted
45-36=9

Hope this helps :)
monicagi
The answer before me was right at first but missed a certain detail.

45/3=15

15x2=30
therefore last week he posted 30 fliers. 45-30 = 15

up to this point 15 are left. 15/5=3
he posted 1/5th of the REMAINING posters which are 15 not 30. 30 is the amount of posters posted the first week

3x1=3 so this week he only posted 3
15-3 = 12
12 are still not posted