Two marathon runners have each trained to run at perfectly consistent paces for the entire 26.2188 \textrm{ mi} of a marathon. Runner A's position along the marathon in miles is a function of how much time has passed in hours, given by a(t)=\frac{19}{4}t. For example, after \frac{12}{19} of an hour (60\frac{\textrm{min}}{\textrm{hr}}\times\frac{12}{19}\textrm{ hr}\approx 38 \textrm{ min}), runner A will have traveled a(\frac{12}{19})=\frac{19}{4}\cdot\frac{12}{19}=3\textrm{ mi}. If runner B finishes the marathon in just \frac{3}{4} the time it takes runner A, then what transformation of Runner A's graph describes the graph of runner B?