## Task 6 - 020716

In a house with 28 windows, some missing shutters need to be procured so that each window has 2 shutters. Some windows still have 2 shutters, the same number of windows are missing both, and the rest have one shutter each.

How many new shutters are needed? Justify your answer!
One can (in thought) attach a shutter to every window that still has two shutters from a window that no longer has any (after all, the number of these two "types" of windows is the same!).

Then every window would have one shutter, and one would be missing everywhere. So 28 new window shutters are needed.

Solutions of the I. Round 1962 adopted from [5]

# 4.4.2 II. Round 1962, Class 7

#### Abstract