20. the traffic lights at three different road crossings change after every 48 sec, 72
sec and 108 sec respectively. if they all change simultaneously at 8: 20: 00 hrs,
when will they again change simultaneously ?

21. a merchant has 120 ltrs of and 180 ltrs of two kinds of oil. he wants the sell oil
by filling the two kinds of oil in tins of equal volumes. what is the greatest of such a
tin.

pls answer i have math exam tmrw
ill give 13 points
pls pls pls pls pls pls