Algebra

let the speed be x 

time be in mins

 so we can form an equation

which is 216x= 225(x-30)

if we expand, we get

216x=225x-6750

so 9x=6750

x=6750/9

=750.

Since the speed is 750 miles per min,

distance= 750*216=162000 miles (per min)

so we have to divide by 60.

162000/60=2700 miles per hour

How many miles is the distance from Penthaven to Jackson?

$v_1=\dfrac{s}{t_1}=\dfrac{s}{108min}\\ t_2=\dfrac{s}{v_1+\dfrac{1mil}{2min}}+\dfrac{s}{v_1-\dfrac{1mil}{2min}}\\ 225min=\dfrac{s}{\dfrac{s}{108min}+\dfrac{1mil}{2min}}+\dfrac{s}{\dfrac{s}{108min}-\dfrac{1mil}{2min}}\\ 225min=\dfrac{s}{\dfrac{s+54mil}{108min}}+\dfrac{s}{\dfrac{s-54mil}{108min}}$

$225min=\dfrac{s\cdot 108min}{s+54mil}+\dfrac{s\cdot 108min}{s-54mil}\\ 225min(s^2-54^2mil^2)=s\cdot 108min(s-54mil+s+54mil)\\ s^2-54^2mil^2=\dfrac{216s^2}{225}\\0.04s^2=54^2mil^2\\ 0.2s=54mil\\ \color{blue}s=270\ mil$

The distance from Penthaven to Jackson is 270 miles.

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