Ladybirds in the Garden

Ladybirds in the Garden printable sheet

In Sam and Jill's garden there are two types of ladybirds. There are red Seven-Spot ladybirds with 7 black spots and black Four-Spot ladybirds with 4 red spots.

Sam and Jill looked at a leaf with three ladybirds on it.

"One Seven-Spot ladybird," said Sam, "and two Four-Spot ones."
"That's 15 spots altogether!" said Jill.
"I wonder if we could find ladybirds whose spots add to other numbers. I know how to do 16."
"And 14 is easy too," added Sam.

How would you make 16 and 14 spots with the Seven-Spot and Four-Spot ladybirds?

What other numbers can you make with adding 4s and 7s?
Can you get lots of numbers from 4 to 35?
Are there some numbers you can't get?