B has the same denominator so there is your answer
"<span>all real numbers between 3 and 10 inclusive" could not be the answer, because these are x-values (values of the independent variable).
"</span><span>all real numbers between 19 and 54 inclusive" is the range. Why? Because in year 3, f(3) = height of tree = 5(3) + 4 = 19 feet.
In year 10, f(10) = 5(10) + 4 = 54 feet. </span>
The answer is: "123454321"
Hope this helps!