n has less than 75 copies
sold 12
so add the 12 back
n had less than 87 copies in the beginning of the day
:)
The recursive formula 
means that the next term in the sequence is 5 more than the previous one.
So, we know that we start from 
, which means that the next term is
Similarly,
I honestly dont know, the only idea I have is to divide 1800 by 4 to see how much.
<span>9x-y=5
rewriting the eqn in the form y = mx+b we get
y = 9x- 5
slope = 9</span>
