The manager of a men's store can sell 43 pairs of socks at a price of $1.05 per pair. If the price is $0.61, he can sell 65 pairs. The total cost to purchase x pairs of socks is c(x)=0.75x+10.5 dollars.
Assuming the demand function is linear, find an equation for D(x).

Question

The manager of a men's store can sell 43 pairs of socks at a price of $1.05 per pair.  If the price is $0.61, he can sell 65 pairs.  The total cost to purchase x pairs of socks is c(x)=0.75x+10.5 dollars. 
Assuming the demand function is linear, find an equation for D(x).

anonymous · Answer

is that supposed to be c(x) = .75x+10.5?

anonymous · Answer

Oh yes! Sorry

anonymous · Answer

so we need to look at the pairs sold as the y-axis and the price as the x-axis.

so we can say that there are two points (.61,65) as (x1,y1)
and we can say that (1.05,43) is (x2,y2)

you can use this to find the slope of the line.  plug in one of the two points to find the equation. 
y = mx + b 
m = (((x1+x2)/2),((y1+y2)/2))