An ant crawls on a coordinate plane, so that the ant's coordinates (:13, y) at time t seconds after it has started crawling are given by mzthm, 3,2327%. Here :1: and y are measured in mm. The temperature of the plane at any point (x, y) is denoted by T(:E, y), measured in "C. It is given that 6T _ 2 2 8T _ $0331 y) _ 11? y 1 and 5y (3:! y) _ 2933}, both measured in 00 per mm. Suppose that when t = 4, the rate of change of temperature experienced by the ant is A 00 per second. Find the value of A