Let's call the two numbers a and b. So we know that the difference of the two numbers is 36:
a - b = 36
And we know that their sum is 286:
a + b = 286
We can use either of these equations to solve for one of the variables in terms of the other variable. Let's use the first and solve for a:
a - b = 36
a = 36 + b
Now we plug this into the other equation and solve for b there:
(36 + b) + b = 286
36 + 2b = 286
2b = 250
b = 125
Answer: The girl herself ran faster than her friend.
Step-by-step explanation:
This answer, of course assumes a lot of variables, but for the sake of keeping things simple, lets assume the following, the people are ran in a "straight line" with no "obstacles" in their way, and ran on the same track.
Calculating in meters-per-second for the girl who ran 200 meters in 28 seconds, you get 7.14285714286 meters per second
Calculating in meters-per-second for the girl who ran 400 meters in 60 seconds, you get 6.66666666667 meters per second
Comparing the two results, it can be "accurately" concluded that the girl herself ran faster than her friend under the following assumptions earlier stated.
