ক ও খ একত্রে একটি কাজ ১০ দিনে শেষ করতে পারে। ক একা কাজটি ১৫ দিনে শেষ করতে পারলে খ একা কাজটি করতে পারে?

ক ও খ একত্রে একটি কাজ ১০ দিনে শেষ করতে পারে। ক একা কাজটি ১৫ দিনে শেষ করতে পারলে খ একা কাজটি করতে পারে? সঠিক উত্তর ৩০ দিনে

For rate - time - distance questions, try to reduce the question to as few unknown quantities as possible. Instead of a separate r, t, and d for each train, look for commonalities: Both trains travel the same distance, so there's only one "d" We don't know the time, but we know that Train Y took less time, since it left an hour and half later. So if Train X took t hours to travel some distance, Train Y only took (t - 1.5) hours. The rates aren't given, but we know that train Y was 4/3 the rate of train X. Let's set it up. Since rate*time = distance and the distances are equal, we can set Train X's rate * time equal to Train Y's rate * time xt = 43x(t−1.5)xt = 43x(t−1.5) Working through the problem, we get xt = 43xt−4/3∗1.5xt = 43xt−4/3∗1.5 here it can be helpful to recognize that 1.5 is just 3232, and cancel out the 3's: 43∗32 = 243∗32 = 2 xt = 43xt−2xt = 43xt−2 Subtract xt from both sides, and add 2 to both sides, and we get: 2 = 13t2 = (1/3)t 6 = t So, adding 6 hours to Train X's starting time, we get 4:00 pm as the time that train Y will catch train X.