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:

After doing the subtraction using a calculator or a pencil and paper, you get that:

So 171 years have passed from 1844 to reach to 2015.
Answer:
-10
Step-by-step explanation:
You have to simplify and then get x
Write two equations with the given information:
1) x = 2y ( x is twice the value of y)
2) x + y = 42
Replace x in the second equation with the value of x in the first equation:
2y + y = 42
Simplify:
3y = 42
Divide both sides by 3:
y = 42 / 3
y = 14
Now we have the value for Y, solve for x by replacing y with 14:
x = 2y
x = 2(14)
x = 28
X = 28 and y = 14