Easy. There is a pattern on the graph. Each baseball card set costs $4. If you add $4 to the $16 (because that is what she will have left after buying 1 baseball card set), you will get $20. So the answer is $20
it’s not an exponential function because it is a quadratic function
an exponential function is y=2^x
X - y = 5....x = 5 + y
6x = 8y
6(5 + y) = 8y
30 + 6y = 8y
30 = 8y - 6y
30 = 2y
15 = y
x - y = 5
x - 15 = 5
x = 15 + 5
x = 20
ur 2 numbers are : 20 and 15
36x^2 will be your answer