If she divides the cookies evenly among 7 plates, 4 cookies are left.
That means it must be 4 more than a multiple of 7.
The multiples of 7 that we can add 4 to and get a result between 24
and 59 are
21, 28, 35, 42, 49
4 more than those are
25, 32, 39, 46, 53
So it has to be one of those five numbers.
If she divides the cookies evenly among 6 plates, 5 cookies are left.
That means it must be 5 more than a multiple of 6
So we will subtract 5 from each of these
25, 32, 39, 46, 53
to see which one gives us a multiple of 6.
20, 27, 34, 41, 48
The only one of those which is a multiple of 6 is 48, which
is what we got when we subtracted 5 from 53.
So the answer is 53.
Edwin
