A linear function is a polynomial function of degree 1 (1,2,3,4,5,6,....) A quadratic function is a polynomial function of degree 2 (1,4,9,16,25,49,64,81,...) A exponential function is not a polynomial function (we may imagine a infinity degree) (1,2,4,8,16,32,64,128,256,512,1024,...)
First, you would notice that they give you the perimeter of it. Meaning 51.4 was a sum of adding the height and base length twice. So you would take 51.4 and subtract 16*2 from it. Which would be 19.4. Next, since 19.4 would be both bases added, and they are both the same, you would do 19.4/2=9.4