In an algebraic equation, you should have at least 2 variables: the independent and the dependent. The independent variable in this case, is the parameter that cannot be controlled - time. This is expressed in minutes using the variable x. The dependent variable is the parameter you want to measure - the distance expressed using the variable y. Since the problem states a parameter of distance in terms of 2 kilometers, y=2. Therefore, I think the choices would be about the amount of minutes it would take for Bradley to cover this distance. Assuming this is the case, then the answer would be:
2 = 2000 - 90x
90x = 2000-2
90x = 1998
x = 1998/90
x = 22.3 minutes
It would take 22.3 minutes for Bradley to cover the 2 kilometers so that he could get home.
