Can someone please show me how to do this question, thank you

I have drawn the picture from my book on paint, hopeing somebody can make sense of my picture.the diagram shows a balance beam with two gymnasts standing on it, labelled A and B. The balance beam has a mass of 40kg and is assumed to be uniform. Gymnast A weighs 35kg and gymnast B weighs 30kg. Determine the reaction at each support.