12 (a) (i) The cost of a book is $x. Write down an expression in terms of x for the number of these books which are bought for $40. (ii) The cost of each book is increased by $2. The number of books which are bought for $40 is now one less than before. Write down an equation in x and show that it simplifics to x + 2x-800. (iii) Solve the equation r2 + 2x - 80=0. (iv) Find the original cost of one book. (b) Magazines cost $m each and newspapers cost $n each. One magazine costs $2.55 more than one newspaper The cost of two magazines is the same as the cost of five newspapers (i) Write down two equations in mand n to show this information (ii) Find the values of m and n.