Answer:
3/35
Explanation:
Here, we want to know the constant of proportionality in this direct variation scenario
Since it is a direct variation, the form we are having would be;
x = ky
where x and y directly vary with each other and k is the constant of proportionality
Now, for the first relation
3 = 35k
for the second
9 = 105k
Thus k would be
3/35 which is the same as 9/105
Kindly note that 9/105 can be reduced to 3/35
So linking the number of weeks to the number of stamps collected, the constant of proportionality is 3/35