Question 1208311
31/7 = 4.4286
7*4 = 28 is too small but 7*5 = 35 fits
131/7 = 18.7143
7*18 = 126 also fits
7*19 = 133 is too large.


The multiples of 7 between 31 and 131 are: {35, 42, 49, ..., 126}
They can be written as {7*5, 7*6, 7*7, ..., 7*12, ..., 7*18}


Cross off 7*6, 7*12 and 7*18 since they involve 6 as a factor.
There are 14 items in the set {5,6,7,...,18} because 18-5+1 = 14. Or you can count out the items.
That must mean there are also 14 items in the set {7*5,7*6,...,7*18} = {35,42,...,126}
We crossed off 3 items {7*6,7*12,7*18} so we have 14-3 = <font color=red>11</font> multiples of 7 between 31 and 131 such that 6 isn't a factor. 


Answer: <font color=red>11</font>