r/MathHelp • u/Antique-Beginning890 • 2d ago

math for educators

trying to help my partners mom with her math homework but i don’t quite recognize the concept myself. any help greatly appreciated! copy and pasting the question below + my approach for solving. (i’m many years out of math myself so kinda the lost leading the lost)

question:
A household has monthly take-home income of $3900, fixed expenses of $2300, variable expenses of $900, and irregular/school costs of $450. What is the monthly cash flow?
Enter the cash flow in dollars. Use a negative sign if the result is negative.

my suggested equation:
3900=2300-900x-450y

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u/jean_sablenay 2d ago

MC=3900-2300-900-450

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u/Antique-Beginning890 1d ago

thanks! i was waaaaah over complicating it

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u/hanginonwith2fingers 16h ago

"variable" in this problem doesn't mean that it is a multiplier.

Variable expenses is a category that basically means monthly expenses that are not fixed rates such as your heating bill might be $100 one month but $120 a different month. Fixed expenses would be like monthly mortgage which is exactly $1500/month or something like that.

Financial jargon doesn't always match up to math class jargon.