The Algol-like program fragment

function f(x) return x+5 

end; function g(y) 

 return 2-y end; 

f(g(2));

can be written as the following lambda expression: (?f. ?g. f (g 2)) (?x. x+5) (?y. 2?y)

Reduce the expression to a normal form. In the reduction, assume that you are supplied with extra rules that allow you to reduce the addition or subtraction of two natural numbers into the corresponding results.