Chatter of sparrows and the Sigma

(2001 korea SAT) function f (x) is f (10) = 50, f (1) = 3 are satisfied,

Sigma is sparrow beak shape chatter to solve.

={f(2)+f(3)+ ... +f(10)}- {f(1)+f(2) + ...+f(9)}

(Like this sigma assignment, chatter)

=f(10)-f(1)= 50-3=47