for both question you want to make the commonly shared variable the same unit as the one it is compared to so for example sunflower to roses is 7 to 6 and roses to lilies is 3 to 5 you would want to make the unit of roses which is the shared variable the same here by multiplying through the ratio with the lesser unit

After which you will want to find the amount of items is in one unit and after finding that you can find how much each item is