You first multiply 7*150 and that is 2100 bars of soaps you need to last 7 days. If there is 150 bars in each case you divide 2100 by 150 and you get 14?. You are using 14 cases for 7 day.
There are 256 possible combinations of fireworks, if they can be repeated in each 4 firework combinations. If they cannot be repeated, there are 24 possible combinations.
