A company makes jewelry. It costs $6,400 to make 10 pieces of jewelry and $11,200 to make 20 pieces of jewelry. Which equation models the cost, C(x), as a linear function of the number of pieces of jewelry, x?

C(x) = 480x + 1600

C(x) = 1600x + 480

C(x) = 480x − 1600

C(x) = 1600x − 480

Question

A company makes jewelry. It costs $6,400 to make 10 pieces of jewelry and $11,200 to make 20 pieces of jewelry. Which equation models the cost, C(x), as a linear function of the number of pieces of jewelry, x?

C(x) = 480x + 1600

C(x) = 1600x + 480

C(x) = 480x − 1600

C(x) = 1600x − 480

ash2326 · Answer

Let cost be C(x) , x is the no. of pieces 
C(x)=Ax+B
A and B are constants that we have to find
it's given it costs $6400 to make 10 pieces
and $11200 to make 20 pieces
let's use the first condition
1st.....6400=10A+B
and then from second condition
2nd.....11200=20A+B
subtract  2nd from 1st
4800=10A
A=480
substutite value of A in 1st to get B
6400=4800+B
B=1600
we get
C(x)=480x+1600
option A