The function for the amount saved if they purchase a used drone rather than a new drone from Jim's store is f(x) = 0.45x
He sells used drones at 70% of the price (x).
So, the selling price of a used drone is:
Express percentage as decimal
Also, he sells new drones at 15% more of the price (x).
So, the selling price of a new drone is:
Express percentage as decimal
The amount saved is the difference between the prices of the drones.
So, we have:
This gives
Subtract
Express as a function
Hence, the function for the amount saved is f(x) = 0.45x
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