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:
200
Step-by-step explanation:
350/7 is 50
50x4 is 200
so 200 out of 350 have pets
Answer:
6am and 9am
I don't have an explination on this but this is the answer if your on khan acedemy
Using the variable x for the unknown number,
20 - (x + 4) = 6
is your answer!
Hope I helped :)