At 210 C the length of the iron bar is 181.5 mm. (b) Write down an equation that shows this second piece of information. (c) Hence, find the length of the iron bar at 40 .C. 5. A building company has many rectangular construction sites, of varying widths, along a road. The area, A, of each site is given by the function A(x) = x(200 - x). where x is the width of the site in metres and 20