Hi to all

I have few short questions if you would like to look at them

a)in how many ways can 3 boys and 3 girls sit in a row?

b)in how many ways can 3 boys and 3 girls sit in the row if the boys and the girls are each to sit together

c)in how many ways if only the boys must sit together?

d)in how many ways if no two people of the same sex are allowed top sit together?

Thank you