Difference between fractional knapsack & greedy solution
The fractional Knapsack problem isn't solved using Dynamic Programming, but can be solved using a greedy algorithm. Item A is \$50/unit, B is \$5/unit and C is \$40/unit. The greedy method is to use as much of the highest value items as possible, which gives the solution on the image.

Dynamic Programming allows you to solve the problem when you cannot split the items.