Interest charge = balance x ( apr/12)
3000 x (.24/12) = 60
Balance = 3000 + 60 = 3060
Minimum payment is total balance x percent for payment:
3060 x 5% = 153
The minimum payment is $153
For the limit approaching 3 from the right, you want to follow the line to the right of x = 3. From the graph you're describing it sounds like that's y = -3.

The RHS limit is -3 even though f(3) = 7
Y intercept is (0,-12), the x-intercept is (4,0)
A nickel is equal to 5 cents or 0.05 dollars.
A quarter is equal to 25 cents or 0.25 dollars.
Let number of nickels be = n
Let number of quarters be = q
...........(1)
As it is given, there are 3 more nickels than quarters so equation becomes,
................(2)
Plug in the value of 'n' from (2) in (1)

= 


As
we get, 
Hence, there are 12 nickels and 9 quarters.