Suppose d ∈ Z. Recall the definition of "equivalence modulo d" in class; for all a, b ∈ Z, a≡b (modd)iffd|(b-a). Supposen,m,x,y∈Z,n≡x (modd)andm≡y (modd). Provethat n+m≡x+y (modd). (Hint: to show this, use the definition; i.e. Show that d | (x + y) - (n + m).)