Different ways of working it out.
Chunking: 18 is 2 less than 20, and 44-20 is easier to work out because 4-2 tens is 2 tens plus the original 4=24. But because we took away 2 more than we needed to, we now add them back: 24+2=26.
Boxes and drawers method: 2-drawer chest, top drawer marked “tens” contains 4 boxes each marked “counters”. Each box countains 10 counters. Bottom drawer marked “counters” contains 4 counters. Chest represents number 44. Need to subtract 18, so take 1 box from top drawer (leaving 3) and discard it. Need to take 8 counters from bottom drawer, but only 4 in drawer, so take box from top drawer (leaving 2) and empty its 10 counters into bottom drawer, making 14 counters. Now we can take away and discard 8 leaving 6. How many in chest? 2 boxes in top drawer and 6 counters in bottom drawer, chest is number 26.
(This is a variation of the tape diagram.)
Formal method: 44-18 says take 8 from 4, but can't do it so borrow a ten and reduce 4 to 3. 4 units becomes 14, take away 8 leaves 6 units. Take 1 from tens to get 2. Answer 26.