Answer: 8
if you're talking about how many bags of sweets you can BUY, as in without counting the ones you got for free, it's 6. if you're talking how much you GOT, it's 8.
Step-by-step explanation: you can multiply 1.5 times an unknown number to get nine. the unknown number would be the number of bag of sweets you get without the "buy 3 get 1 free" thing. You can reverse the equation to get 9 divided by 1.5 equals 6.
you can then divide 6 by three, which is 2- meaning you got two free bags of sweets. 6 plus 2 is 8.