(a) First half of the distance is covered at 3/4th of its original speed. Then, Vidya taken 4/3 of its original time to cover half of the distance. So, Vidya takes 1/3 extra time during her first half journey. Now, she is left with (1−
1
3
) of the time to cover her remaining half distance = 2/3rd of the time. So, she can cover the distance at 3/2 times of her usual speed