Just looking at your examples, some thoughts that may help are as follows:
I’m assuming triplets don’t give you too much trouble. They’re pretty straightforward.
For the larger groupings, based on your example page, you could think through the following if you get lost:
- For simple (duple) meter, find the largest number of notes in the grouping divisible by 4. Whatever the duration of that grouping is is the duration of your tuplet.
EXAMPLE: For a grouping of 9 sixteenths, the largest number of sixteenths in that grouping divisible by 4 is 8. 8 sixteenths equals 2 quarter notes, so your grouping fits into the space of two quarter notes.
- For compound meter, do the above but use multiples of 3 instead of 4.
EXAMPLE: For an grouping of 8 sixteenths, the largest number of sixteenths in that grouping divisible by 3 is 6. 6 sixteenths equals a dotted quarter, so your grouping fits into the space of a dotted quarter.
Hopefully this helps!