(a) Find natural numbers a and b so that (b) It is true that 1 1 1 == - + n a b 2 1 5 + n 3 3 n Observe that if 5 | n the right hand side reduces to the sum of two unit fractions. If 7 | n, conjecture a similar formula for fractions of the form 2/n and prove that your conjecture is correct. (c) Show that 3/7 cannot be expressed as a sum of two unit fractions with different denominators.