It would be 20 each person. But, I don't think you completed the question.
"T<u>he function is decreasing":</u>
This means the slope of the function will be negative at the given point. Anywhere the line is going down, from left to right, is decreasing. This eliminates choices A and C.
<u>"The function is concave down":</u>
This means the curve of the function will be open down (think of an upside down u). This eliminates choice E.
<u>"f(x)>0":</u>
This is anywhere the curve is above the x axis. This eliminates choice D.
The answer is Choice B) x=2.
Hope this helps!!
The age difference between Diane and Amy remains the same. 6 year later, the age difference is still 23 years old.
6 years later,
Amy is 23 years old
Diane is 46 years old
Now,
Amy, 17 years old
Diane, 40 years old.