A bus traveled on the highway and on local roads to complete a trip of 160 miles. The trip took 4 hours. The bus traveled at an average speed of 55 miles per hour (mph) on the highway and an average speed of 25 mph on local roads. If $\bm{x}$ is the time, in hours, the bus traveled on the highway and $\bm{y}$ is the time, in hours, it traveled on local roads, which system of equations represents this situation?