Please help (circle proofs)

What is sin 7x/4 ? i need on this urgent trig

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)

Let u = {q, r, s, t, u, v, w, x, y, z} a = {q, s, u, w, y} b = {q, s, y, z} c = {v, w, x, y, z}. list the elements in the set.a ∩ (b ∪ c)a) {q, s, w, y}b) {q, y, z}c) {q, s, u, w, y, z}d) {q, r, w, y, z}