Final answer:
The equation of variation where c varies jointly as g and f is c = kgf. To find the value of k, we use the given information and solve for k.
Step-by-step explanation:
The equation of variation where c varies jointly as g and f is c = kgf. To find the value of k, we can use the given information that c = 24 when g = 2 and f = 3. Plugging these values into the equation, we get 24 = 2k(3). Simplifying, we have 24 = 6k. Dividing both sides by 6, we find k = 4. Therefore, the equation of variation is c = 4gf.