David W. answered 08/08/15
Tutor
4.7
(90)
Experienced Prof
Let X be the "how much more?" that the problem wants us to find.
Then, we add X to the amount of purchases so far, to get the total revenue to be at least $1,200. That looks like this:
$917.26 + X ≥ $1,200
X ≥ $1200 - 917.26 (subtract 917.26 from both sides does not change inequality)
X ≥ $282.74