How do you write an algebraic expression that models the word phrase "The amount of money you spent if you started with $40 and now have d dollars"?

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Answer 1 · 2016-01-23T11:17:46

Let's call the amount spent $s$

We know that the amount spent and the amount left adds up to $$40$ , or in formula-form: $s+d=40$

Or in another form (by subtracting $d$ on both sides):
$s=40-d$

Answer 2 · 2016-01-23T11:19:15

40 - a = d

let the amount of money spent be a

started with 40 and spent a is represented by : 40 - a

left with d , hence 40 - a = d