Easy problem, but no idea how to solve it?

[Gramsci]

Homework Statement

A motorbike with the velocity 40km/h is able to stop at a distance, D, when it brakes with maximal deacceleration. At what distance will a car with a velocity of 60 km/h stop?

Homework Equations

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The Attempt at a Solution

I was trying to solve it through regular equations such as at^2=distance, but there seems to be too many unknowns. Any ideas?

 

[rl.bhat]

Use v^2 - u^2 = 2as. Find a in terms of D. Here u = 40 km/hr and v = 0. Use this a and find the distance for 60 km/hr using the above equation.