Each person would receive 1 and an half cookies.
in other words 1 1/2
Tnemos el sisema de ecuaciones:

Podemos resolverlo por eliminación sumando ambas ecuaciones y eliminando y. Asi podemos resolver para x:

Ahora podemos resolver para y con cualquiera de las dos ecuaciones:

Respuesta: x=-3, y=0
Let's call that number x, twice the number will be 2x, sum of it and 5 is, 2x+5. So if this expression is at most 15, it means, it can be only less than 15 and equal to 15. Let's show this as an inequality.

Let's solve.

![x\quad \in \quad \left[ -\infty ,5 \right]](https://tex.z-dn.net/?f=x%5Cquad%20%5Cin%20%5Cquad%20%5Cleft%5B%20-%5Cinfty%20%2C5%20%5Cright%5D%20)
If the number is a natural number. The values it can take is,
You can divide them or simply subtract depending on the objects. If more information was provided I could give you a better answer.
There will be 121 handshakes because 11 times 11 is 121