The left hand side of pic related is the n=2 case of
?(±x1±x2±...+xn)
which is the product of all possible (distinct) sums of x1,x2,...,xn, so that xn has coefficient 1 and the rest have coefficient either 1 or -1.

For the n=3 case the above product is
(x1+x2+x3)(-x1+x2+x3)(x1-x2+x3)(-x1-x2+x3).

For the n=4 case the above product is
(x1+x2+x3+x4)(-x1+x2+x3+x4)(x1-x2+x3+x4)(x1+x2-x3+x4)(-x1-x2+x3+x4)(-x1+x2-x3+x4)(x1-x2-x3+x4)(-x1-x2-x3+x4)

The problem is to expand the above product in the case where n is equal to your country's age of consent.