Answer:
14 gel pens/minute
Step-by-step explanation:
divide the amount by time.
210/15 = 14
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:
Had two congruent sides
Has congruent base angles