Question 1185074
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f(n)=f(n−1)−f(n−2)<br>
This means f(n), the n-th term in the sequence, is the difference between f(n-1), the (n-1)th term (the previous term), and f(n-2), the (n-2)th term (the term two previous).<br>
So f(3)=f(2)-f(1); and you are given f(2) and f(1), so you can find f(3).<br>
Then f(4)=f(3)-f(2); and you now have values for both of those, so you can find f(4).<br>