Good day to all!
There is the following task:
McDonalds sells roast chicken in 6, 9, and 20 chunks in portions. It is possible to buy exactly 15 pieces (if you buy a portion of 6 and 9 pieces). But exactly 16 cannot be bought, because no combination of the sums of positive values of 6, 9, and 20 will result in 16.
The task is to write a function that counts for any number n, whether it is possible or not to buy exactly n pieces of chicken: 6a + 9b + 20c = n ////
a, b, c can be natural numbers or 0.
There are no problems with programming, but from a mathematical point of view, I have no idea how to approach this. For any idea how to count it, I will be very grateful !!!!!