Found this on another forum. Maths undergraduate drawing a blank on his niece's 'Year 7' homework problem. Ashamed to say I'm also drawing a blank, although I'm meant to be able to teach Year 7! Perhaps we're both missing something obvious and trying to make it more complicated than it is. 'In a class, one-third of the pupils bring a teddy to school. During the term, each boy took 12 books out of the library, each girl 17 and each teddy 9. In total, 305 books were taken out. How many girls are in the class?' Need a 'Year 7-friendly' way of solving it.