I think d problem here is of understandn/application of words.'OF' here in particular.I teach d children across classes Maths as well.Knowingfully well d problem of applyn d meanings ordinary common english words in maths class/questions,this hz somewt forcd me upgrade my english language knowledge&payd a closer study of maths txtbooks/workbooks/guidebook/videos/forums etc.Maths teachers ll understand my point here