problem :

they are 40 baby, 18 like banana, 25 like mangoes, 9 like them, how many for baby not like banana & mangoes?

n{AΛB} = (n{A} + n{B}) - (n{S} - n{X})

9 = (18 + 25) - (40 - n{X})

9 = 43 - 40 + n{X}

9 = - 3 + n{X}

9 + 3 = n{X} =

n{X} = 12 ???

i think the answer is incorrect? How to make it right?

thanks...

zidan