shop sells pencils in packs and in boxes. There are 4 pencils in a pack and 12 pencils in a box. Lola buys d packs of pencils. (a) Write down an expression, in terms of d, for the number of pencils Lola buys. (1) Rory buys x packs of pencils and y boxes of pencils. (b) Write down an expression, in terms of x and y, for the total number of pencils Rory buys.