Im a bit stuck in both these questions

Let u, I!) = 111(3u + 21.!) where u(a:, y] = 5:1:y and etc, 3;) = y2. To four decimal planes, use the Chain rule\") to nd % when I =1a.11d y =1. {*1 Remark. In this question, you are not allowed to directly substitute is end 1; in f to obtain e new function of :1: and y