Let
x--------> the time in hours
y-------> the distance in miles
we know that
The speed is equal to
in this problem
<u>Equation First Train</u>
<u>Equation Second Train</u>
---------> equation 
Substitute the values of 
and 
in the equation
Solve for x
therefore
<u>the answer is</u>
Explanation:
1. Identify the different constellations of variables. Here there are three:
2. Combine coefficients of each of the different variable constellations:
(8.1 -2.8)b +(6.7 +0.9)a +(2.5 +7)
5.3b +7.8a +9.5
3. Perform any other operations that might be required depending on the sort of equivalent wanted. For example, one could write ...
5.3(b +(78/53)a) +9.5 . . . . . . . shows the weight of a relative to b
Let one of the numbers be x. The other number cab then be represented as 36-x (x+36-x = 36).
The product can then be represented as y = x(36-x) or y=36x-x2
The maximum or minimum is always on the axis of symmetry which has the formula x=-b/2a.
In our case, the axis of symmetry is -36/-2, so x=18.
If one number is 18 and the 2 numbers add to 36, the other number is 18 as well.
So the 2 numbers are 18 and 18 and the maximum product is 324,
