How to ask these kind of questions in English?
When you think it is impossible that the situation is happening.

¿Cómo no van a saber cuanto es 1 + 1? Someone doesn't know that easy question above, you say...

¿Cómo no van a tener jabón en el baño?
You walk into the bathroom and don't find soap, you say...

Question

How to ask these kind of questions in English?
When you think it is impossible that the situation is happening.

¿Cómo no van a saber cuanto es 1 + 1? Someone doesn't know that easy question above, you say...

¿Cómo no van a tener jabón en el baño? 
You walk into the bathroom and don't find soap, you say...

Answer

Idk if I understood you right... but:

How can you not know 1+1?
How can you not have soap in your bathroom?

Is this what you were looking for?!

Answer

Hola Carlos,

Espero que estés bien! En ingles, nunca usamos esa frase 'You walk into the bathroom and don't find soap' aunque tiene sentido gramatical.

Más común y natural sería 'You don't need to be a rocket scientist to understand that..."

Espero que este te ayude!