Answer:
The amount earned is $327.75
Step-by-step explanation:
If the workwr working for 5h gets $71.25, then his working for 1 hour could be said to be x.
5h = $71.25
1h = x; cross multiplying would result in
x= 
x= $14.25 which is the pay for 1h
Therefore for 23 h the worker would earn
23* 14.25 = $327.75
It follows from the definition of the binomial coefficient:

So we have

That is,
gets absorbed into the numerator's factorial, and we introduct
into the denominator. Now,
, so we get

as required.
the Answer is D ( just look at where the x and y coords line up)
Sum of all interior angles on a polygon is
180( n - 2) n = number of sides in the polygon.
now, this one is is a 21-gon, thus the sum is 180( 21 - 2).