The equation governiong this relationship is y = kx. Since y = 25 when x = 60,
25 = 60k, and k=(5/12). Thus, the equation is y = (5/12)x.
If y = 30, then 30 = (5/12)x. Mult. both sides by 12/5 to obtain the value of x:
(12/5)(30) = 360/5 = 72
There really is no single "obvious" choice here...
Possibly the sequence is periodic, with seven copies of -1 followed by six copies of 0, or perhaps seven -1s and seven 0s. Or maybe seven -1s, followed by six 0s, then five 1s, and so on, but after a certain point it would seem we have to have negative copies of a number, which is meaningless.
Or maybe it's not periodic, and every seventh value in the sequence is incremented by 1? Who knows?
I'll go ahead and assume the latter case, that the sequence is not periodic, since that's technically somewhat easier to manage. We can assign the following rule to the

-th term in the sequence:


for

.
So the generating function for this sequence might be

As to what is meant by "closed form", I'm not sure. Would this answer be acceptable? Or do you need to find a possibly more tractable form for the coefficient not in terms of the floor function?
Make the 3 into a fraction and then flip it to cancel out which makes it easier then do it to the -2,197 for you to get x
Given ---›
y = -3
&
y = x - 0.8
So,
=> x = y + 0.8
=> x = -3 + 0.8
=> x = -2.2
Therefore, the best approximation for the solution to this system of equations is = (–2.2, –3)

= -7 Multiply both sides by 10
x = -70
C. x = -70