Answer:
34 + 8n
Step-by-step explanation:
a₁ = 42

a₂ = a₁ + 8 = 42 + 8 = 50
a₃ = a₂ + 8 = 50 + 8 = 58
a₄ = a₃ + 8 = 58 + 8 = 66
Arithmetic sequence: 42, 50 , 58 , 66, ......
a₁ = 42 ; d = 8
= a₁ + d(n-1)
= 42 + 8(n - 1)
= 42 + 8n - 8
= 34 + 8n
Whers the picture my guy?
We can put this information into two equations:
7 booklets = 140 stamps
3 booklets = 60 stamps
Let us then focus on one equation to find the relationship:
7 booklets = 140 stamps
If we put that into a fraction, we get

or

.
This means that for every booklet, Ashley gets 20 stamps; or rather, each booklet has 20 stamps.
We can then see that this relationship holds true for the second equation as well:

or

.
To write a general equation for this relationship using
p for the number of postage stamps, and
b for the number of booklets:
p = 20b
Where
b is equal to
p.
Note that this just produces three parametric equations:



In the

plane, this is just he parametric equation for an ellipse (as a function of u). The z is simply a linear function.
The surface is then an ellipse extruded along the z-axis. We get a elliptic cylinder.