Can you guys help me out with this With Solutions
Please I need it urgently

a) Three bells ring at the intervals of 10, 15 and 20 minutes respectively. If they all ring at 10:00 a. m. at once, at what time will they ring together again ?

b) Three measuring tapes are of 24 m, 32 m and 48 m long. Find the shortest length that can be measured exactly by any one of these tapes.

c) A book, a pen and an exercise book cost Rs 50, Rs 25 and Rs 20 respectively. Find the smallest sum of money with which exact number of books, pens and exercise books can be purchase.