Arithmetic is frustrating is an example of PREDICATE POSITION. There are three positions where an adjective can be placed in a sentence: before a noun, after a noun or in the predicate. These positions are termed attrubutive, appopositive and predicate positions respectively. An adjective is in a predicate position when it is placed in the predicate of a sentence. The adjective in the given sentence is 'frustrating'.
Allusion because it's <span>an expression designed to call something to mind without mentioning it explicitly; an indirect or passing reference.</span>
