(Strip Number 172, Original Publication Date, 16 September 1981)
Panel 1: John's eyes are almost out on stalks as he looks at Elly's jumbled-up records and tells her "Look at this! Unrecorded checks, no numbers, no dates....and where are your deposits?"
Panel 2: He next asks her how she expects to get an accurate balance with a system like the one she's using.
Panel 3: She smiles and says "This is a system?" as if being disorganized is a thing to be proud of; John is wincing in pain at being lectured about the importance of budgeting by someone who's always complaining about how hard math is.
Summary: Tomorrow's strip, in which he makes a nasty pun about her feckless inability to do basic arithmetic, puts a punctuation mark on the 'stereo' arc; after all, she was the one running her mouth about saving money and she doesn't even know for sure how much she has. He does know how much he can spend on things and it galls him to be told about being improvident by someone who still uses the adjective 'electronic' to describe calculators.
ETA: Now that annotations to the strip have become a fixture, I should think that she'd explain that Rod pretty much had to take care of the bills because as an artist, she couldn't do math or use computers.