This will be a fairly unusual request but hopefully it jogs someone's memory!
When I was a young child in the early Nineties my mother used to play an educational cassette tape during car journeys - "Simple Sums". It was a sing-along audio adventure where a boy and a girl would recite arithmetic with The Professor. I can remember the lyrics of the opening jingle of the tape very distinctly:
"Sums, sums, simple sums
Sing-a-long and have some fun
Add and take-away
You can learn the easy way
Listen carefully
Try to sing-a-long with me
When you go to school
You'll know what to do"
I thought this would be a good thing to jumpstart my own young ones, it'd at least be a change from Cocomelon on repeat, but it course, this was thirty years ago: the cassette I listened to back then is long gone and try as I might I can't find hide nor hair of a copy of it anywhere, I couldn't say who made it or exactly when it was made - even searching for the lyrics on YouTube brings up nothing.
Would anyone else happen to remember "Simple Sums" or something similar and be able to provide more guidance on it?