A good way to practice s d t problems is in the car on motorway journeys. Use the miles to go signs you regularly pass, i.e. 43 miles to Hungerford, I am travelling at 70mph how long will it take? Or, I am 102 miles from Nottingham I want to arrive there at 1300, what speed should I travel at?
These sorts of questions got me through flying training and certainly sharpen up your skills with this sort of problem.