Use what you know about addition to find:

$5+4=\editable{}$5+4=

We know that:

$5+4=9$5+4=9.

Use this to find:

$15+4=\editable{}$15+4=

We know that

$5+14=\editable{}$5+14=

$17+2=19$17+2=19

$3+15=18$3+15=18

Fill in the boxes with the missing numbers.