
Find the missing number from the given alternatives.
| 6 | 10 | 14 |
| 9 | 15 | 21 |
| 12 | 20 | ? |



Rearrange the following parts to form a meaningful and grammatically correct sentence:
P. a healthy diet and regular exercise
Q. are important habits
R. that help maintain good physical and mental health
S. especially in today's busy world