STEPS:
1) Find how many parents answered naughty- find 26% of 150
0.26 x 150 = 39
So 39 parents answered NAUGHTY.
2) Find how many parents answered nice- find 70% of 150
0.7 x 150 = 105
So 105 parents answered NICE.
3) Now add how many parents answered nice and naughty:
105 + 39 = 144
4) Now do the difference between this number and the total number of parents to find how many parents didn't answer:
150-144 = 6
SO, 6 parents did not answer either naughty or nice.