If Rati travels at his usual speed for ‘x’ km/hours, he covers the same distance as he covered when he travels at a speed 30 km/hr less than usual, but for (t + 3) hours. Which of the following can be determined?

(A) If he travels at 20 km/hr less speed than usual, he can cover a distance of 240 km in (t - 1) hours. What is the value of ‘x’?

(B) If travels at his usual speed for (t + 2) hours, and at 50% of his usual speed for (t - 2) hours, his average speed for the journey is 68 km/hr. What is his usual speed?

(C) His usual speed (in km/hr) is a multiple of 5 between 40 and 50 (both inclusive). If ‘t’ is a whole number, what is his usual speed?

(D) If he travels at his usual speed for ‘t’ hours, he covers a distance of 400 km. What is the value of ‘x’?