It will be irrational. The sum of any irrational and rational number will ALWAYS result in a irrational answer. Khan Academy has a video on this if you want to watch it.
To find the number of years between 1844 to 2015 you have to subtract.
Lets say that x is the # of years in between 1844 and 2015
Then we have:
![\sf{2015 - 1844 =x}](https://tex.z-dn.net/?f=%5Csf%7B2015%20-%201844%20%3Dx%7D)
After doing the subtraction using a calculator or a pencil and paper, you get that:
![\huge{\boxed{\bf{x=171}}}](https://tex.z-dn.net/?f=%5Chuge%7B%5Cboxed%7B%5Cbf%7Bx%3D171%7D%7D%7D)
So 171 years have passed from 1844 to reach to 2015.
The answer i believe is C
Roots is another name for the x-intercepts