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"?
Let's call the amount spent
We know that the amount spent and the amount left adds up to
Or in another form (by subtracting
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