If n is an integer, f(n) = f(n-1) - n and f(4)=15. What is the value of f(6)?	Pick one:	A) 4	B) 0	C) 1	D) 2	E) 24
Since f(n)=f(n-1)-n then: f(6)=f(5)-6 and f(5)=f(4)-5.   As given that f(4)=15 then f(5)=15-5= 
<gadget id="calculator">15-5</gadget>
<output>10</output>
10 --&gt; substitute the value of f(5) back into the first equation: f(6)=f(5)-6=10-6= 
<gadget id="calculator">10-6</gadget>
<output>4</output>
4.   Answer: A.   Questions on funtions to practice:
<result>A</result>
If n is an integer, f(n) = f(n-1) - n and f(4)=15. What is the value of f(6)?