Answer: 6 students hate potatoes.
Step-by-step explanation:
The Venn diagram representing the situation is shown in the attached photo.
Set M represents the set of students that like mashed potatoes.
Set F represents the set of students that like French fried potatoes.
Set T represents the set of students that like Twice-baked potatoes.
H represents the number of students that hate potatoes.
3 liked all three styles
The number of students that like mashed and twice baked potatoes only is 6 - 3 = 3
The number of students that like mashed and French fried potatoes only is 12 - 3 = 9
The number of students that like twice baked and French fried potatoes only is 5 - 3 = 2
The number of students that like mashed potatoes only is 15 - (9 + 3 + 3) = 0
The number of students that like French fried potatoes only is 20 - (9 + 3 + 2) = 6
The number of students that like twice baked potatoes only is 9 - (3 + 3 + 2) = 1
Since the total number of students is 30, it means that
0 + 6 + 1 + 3 + 9 + 2 + 3 + H = 30
24 + H = 30
H = 30 - 24
H = 6