Complex sentence: Every decision problem is reducible to a computation problem in the following way, since every class of yes-or-no questions is reducible to the predicate form "Is P (x_1,..., x_n) true?".
Split into simpler sentences: Every decision problem is reducible to a computation problem in the following way. Every class of yes-or-no questions is reducible to the predicate form "Is P (x_1,..., x_n) true?".