It seems that "John" and "Bob" have somehow morphed into "Grogg" and "Winnie"...
But, anyway.....call the number of minutes that one of tthem could be late = x
And call the number of minutes that the other could be late = y
So......the total possible minutes that they could be late is 60 minutes each...so...we have this equation of a line
x + y ≤ 120 (1)
But....we are looking for this x + y ≤ 45 (2)
Look at the graph here : https://www.desmos.com/calculator/90isasjiab
The area of the triangle formed by (1) in the first quadrant is (1/2)base * height =
(1`/ 2) (120) (120) = 14400 / 2 = 7200 units^2
The area of (2) in the first quadrant is (1/2)(45) (45) = 1012.5 units^2
So....the probability that the sum of the minutes that both are late is ≤ 45 is
1012.5 / 7200 = 9 / 64