This is already in simplest form. it can't be reduced furthermore.
As a mixed number is 5 1/4
As a decimal is 5.25
In general, the volume

has total derivative

If the cylinder's height is kept constant, then

and we have

which is to say,

and

are directly proportional by a factor equivalent to the lateral surface area of the cylinder (

).
Meanwhile, if the cylinder's radius is kept fixed, then

since

. In other words,

and

are directly proportional by a factor of the surface area of the cylinder's circular face (

).
Finally, the general case (

and

not constant), you can see from the total derivative that

is affected by both

and

in combination.
<h3>hello!</h3>
Plug in the values of x and solve for y:-
y=5+4x
y=5+4(4)
y=5+16
y=21
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y=5+4x
y=5+5(5)
y=5+20
y=25
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y=5+4x
y=5+4(8)
y=5+32
y=37
___________________________________
y=5+4x
y=5+4(10)
y=5+40
y=45
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<h3>note:-</h3>
Hope everything is clear; if you need any clarification/explanation, kindly let me know, and I will comment and/or edit my answer :)