Question 71569
Use the formula d=rt.

John will catch Martina when their distances are the same.

Distance Martina travels is 24t

John's distance is 48(t-2), because he travelled 2 hours less but at a greater rate.

Distance are equal. 

{{{24t=48(t-2)}}}

{{{24t=48t-96}}}

{{{96=24t}}}

{{{t=4}}}

In 4 hours, from Martina's starting time, John will catch her.

Therefore, 9 AM + 4 hours = 1 PM