# Math Help - Necklace Maker

1. ## Necklace Maker

John makes and sells necklaces. He has observed over time that when the price is $8 each, he sells an average of 36 per day. If he increases the price, then his average sales fall by 3 per day for each dollar increase. The materials for each necklace cost$4. Express his profit P as a function of x, the number of necklaces sold.

P(x) = ?

2. revenue, R = (8+x)(36-3x)

cost, C = 4x

profit = revenue - cost

3. ## Necklaces

John makes and sells necklaces. He has observed over time that when the price is $8 each, he sells an average of 36 per day. If he increases the price, then his average sales fall by 3 per day for each dollar increase. The materials for each necklace cost$4. Express his profit P as a function of x, the number of necklaces sold.

I tried that:
Revenue: (8+x)(36-3x)
Cost: 4x
So Profit: (8+x)(36-3*x)-4*x

But it is incorrect because i am using X to detonate a price increase, whereas x should be used to detonate the number of necklaces sold..

How do you do that?

4. Originally Posted by gearshifter
John makes and sells necklaces. He has observed over time that when the price is $8 each, he sells an average of 36 per day. If he increases the price, then his average sales fall by 3 per day for each dollar increase. The materials for each necklace cost$4. Express his profit P as a function of x, the number of necklaces sold.

P(x) = ?
A very very similar question has previously been asked by another member and replied to: http://www.mathhelpforum.com/math-he...n-formula.html

5. Originally Posted by skeeter
revenue, R = (8+x)(36-3x)

cost, C = 4x

profit = revenue - cost
my mistake ... cost should be C = 4(36-3x), not 4x. my apologies.