This math problem is very difficult. How soon can Xiao Xin catch up with Xiaoming?
(1)0.4×2=0.8 (hours) 3.4-0.8=2.6 (hours) 2.6× 2 = 5.2 (kilometers) 5.2-1.8-1.7-/kloc-0. The distance between rooms D is x (1.7+1.8+x+1.1)/2+0.4 * 2 = 3.4 (4.6+x))/2+0.4 * 2 = 3.