Question 762909
We use the data to determine a line:

{{{
m=(y[2]-y[1]  )/(x[2]-x[1]  )=(1680-1500)/(50.80-50.40)=450
}}}


and using the first pair of data we can write:


{{{
y-1500 = 325(x-50.40)
}}}


Now when y=1840 we get


{{{
1840-1500 = 450(x-50.40)
}}}



When we solve for x we get x=$51.16


:)