Final answer:
To calculate the dosage for a heartworm preventative for a 23lb dog using the formula D(x)= 136/25x, substitute x with 23 to get 5.472 milligrams as the required dosage.
Step-by-step explanation:
The dosage in milligrams D of a heartworm preventative for a dog who weighs x pounds is given by the function D(x)= 136/25x. To find the proper dosage for a dog that weighs 23lbs, we simply plug the weight of the dog into the function:
D(23) = 136/25 * 23
Now calculate the right side:
(136/25) * 23 = 136/23
Perform the multiplication:
136/25 * 23 = 5.472
Therefore, the proper dosage for a dog that weighs 23 pounds is 5.472 milligrams.