Pens are sold in small packs and large packs. There are 12 pens in a small pack. There are 50 pens in a large pack. Lucas buys s s\,s small packs and l l\,l large packs of pens.
Write an expression for the total number of pens Lucas buys.
64 exam-style questions on WJEC GCSE Maths Writing an Expression. Each one has a worked solution and a mark scheme showing where the marks go.