There are 12 pupils in a class they are each asked if they have a brother or sister 9 say they have a brother 7 say they have a sister 2 say neither fill in the Venn diagram

1/800 is the right answer

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: