We know that Ava is paying $2 dollars per week so if L is the money that she owes and t is the number of weeks, and I is the initial debt so we can write an equation like:

Now we can replace the info we have to find the value of I so:

and we solve for I

So the final equation will be:
My dear that is solution:
2x=3x-1
-x=-1
X=1
24/100 like NewTube
30/100 like Friendspace
14/100 like NaviChat
12/100 like other
20/100 like none
100 - 20 = 80
Therefore, exactly 80% of the grandparents have a favourite social media website. The first statement is most likely to be correct