This is a speed, distance, time problem
rule of thumb always work in the values you're trying to find. In this case seconds, so you need to convert he distances to seconds.
Here's a calculator that will give you your answers, just plug in the right numbers
Here's the Algebra Website with the formulas needed to do the algebraic representation of distance.
The simple formula for distance time and speed is http://www.purplemath.com/modules/distance.htm
http://www.machinehead-software.co.uk/bike/speed_distance_time_calc.html