A bottle of the medicine contains 0.5 kilograms of the medicine. One dose of the medicine is 20 grams for a child and 45 grams for an adult. The number of grams used can be calculated with the formula 20C + 45A, where A is the number of adult doses and C is the number of child doses. If a medical assistant needs to give a dose of the medicine to 12 adults and 10 children, will there be enough medicine in the bottle? If not, how many more grams will be needed?

So this is what we know:
There are only 0.5 kilograms of medicine in the bottle
1 child dose = 20 grams1 adult dose = 45 grams
We need to give 12 adults and 10 children the medicine, so c = 10 and a = 12
Inserting that those values into the formula, you get a total of 740 grams
740 grams = 0.74 kilograms
Because 0.74 > 0.5 grams in the bottle, there is not enough medicine in the bottle.
To find out how much more you will need, subtract 0.5 from 0.74 to get 0.24.
You need an additional 0.24 kilograms of the medicine to help all of the people.