logic
posted by Anonymous .
Out on my street, there are a certain number of pigeons sitting on telephone poles. If there were exactly 2 pigeons sitting on each telephone pole, then 1 pigeon would have no space to sit on. If there were exactly 3 pigeons sitting on each telephone pole, then there would be 1 telephone pole with no pigeons on. How many pigeons were there?

3?

Let x = # of poles
2x + 1 = 3(x_1)
2 pigeons per pole with 1 pigeon
3 pigeons per poles with 1 less pole.
2x + 1 = 3x 3
x = 4 poles
You have 2 pigeons per pool = 8 pigeons + one left over = 9 pigeons.
3 pigeons per pole = 9 pigeons.
It looks like we have nine pigeons.